Multiplexed Analysis Of Polymorphic Loci By Concurrent Interrogation And Enzyme-Medicated Detection

ABSTRACT

The invention provides methods and processes for the identification of polymorphisms at one or more designated sites, without interference from non-designated sites located within proximity of such designated sites. Probes are provided capable of interrogation of such designated sites in order to determine the composition of each such designated site. By the methods of this invention, one or more mutations within the CFTR gene and the HLA gene complex can be identified.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application Ser.No. 60/329,427 filed Oct. 14, 2001, U.S. Provisional Application Ser.No. 60/329,620, filed Oct. 15, 2001, U.S. Provisional Application Ser.No. 60/329,428, filed Oct. 14, 2001 and U.S. Provisional ApplicationSer. No. 60/329,619 filed Oct. 15, 2001. This application is related toPCT application Serial Number PCT/US02/______ of the same title filedconcurrently herewith. All the above-referenced applications areexpressly incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to molecular diagnostics andgenetic typing or profiling. The invention relates to methods, processesand probes for the multiplexed analysis of highly polymorphic genes. Theinvention also relates to the molecular typing and profiling of theHuman Leukocyte Antigen (HLA) gene complex and the Cystic FibrosisConductance Trans-membrane Regulator gene (CFTR) and to compositions,methods and designs relating thereto.

BACKGROUND OF THE INVENTION

The ability to efficiently, rapidly and unambiguously analyzepolymorphisms in the nucleic acid sequences of a gene of interest playsan important role in the development of molecular diagnostic assays, theapplications of which includes genetic testing, carrier screening,genotyping or genetic profiling, and identity testing. For example, itis the objective of genetic testing and carrier screening to determinewhether mutations associated with a particular disease are present in agene of interest. The analysis of polymorphic loci, whether or not thesecomprise mutations known to cause disease, generally provides clinicalbenefit, as for example in the context of pharmacogenomic genotyping orin the context of HLA molecular typing, in which the degree of allelematching in the HLA loci of transplant donor and prospective recipientis determined in context of allogeneic tissue and bone marrowtransplantation.

The multiplexed analysis of polymorphisms while desirable infacilitating the analysis of a high volume of patient samples, faces aconsiderable level of complexity which will likely increase as newpolymorphisms, genetic markers and mutations are identified and must beincluded in the analysis. The limitations of current methods to handlethis complexity in a multiplexed format of analysis so as to ensurereliable assay performance while accommodating high sample volume, andthe consequent need for novel methods of multiplexed analysis ofpolymorphisms and mutations is the subject of the present invention. Byway of example, the genetic loci encoding Cystic Fibrosis TransmembraneConductance (CFTR) channel and Human Leukocyte Antigens (HLA) areanalyzed by the methods of the invention. Cystic fibrosis (CF) is one ofthe most common recessive disorders in Caucasians with a rate ofoccurrence in the US of 1 in 2000 live births. About 4% of thepopulation carry one of the CF mutations. The CFTR gene is highlyvariable: more than 900 mutations have been identified to date (seehttp://www.genet.sickkids.on.ca/cftr, which is incorporated herein byreference). The characterization of the CFTR gene provides the key tothe molecular diagnosis of CF by facilitating the development ofsequence-specific probes (Rommens et al., 1989; Riordan, et al., 1989;Kerem et al., 1989, each of which is incorporated herein by reference).The National Institutes of Health (NIH)— sponsored consensus developmentconference recommended carrier screening for CFTR mutations for adultswith a positive family history of CF (NIH 1997). The committee oncarrier screening of the American College of Medical Genetics (ACMG) hasrecommended for use in general population carrier screening a pan-ethnicmutation panel that includes a set of 25 disease-causing CF mutationswith an allele frequency of >0.1% in the general population of UnitedStates (see http://www.faseb.org/genetics/acmg, which is incorporatedherein by reference). The mutations in the ACMG panel also include themost common mutations in Ashkenazi Jewish and African-Americanpopulations.

Several methods have been described for the detection of CFTR mutationsincluding the following: denaturing gradient gel electrophoresis (Devotoet al., 1991); single strand conformation polymorphism analysis (Pliethet al., 1992); RFLP (Friedman et al., 1991); amplification withallele-specific primers (ASPs) (Gremonesi et al., 1992), and probingwith allele specific oligonucleotides (ASO) (Saiki et al., 1986). Awidely used method involves PCR amplification followed by blotting ofamplified target strands onto a membrane and probing of strands witholigonucleotides designed to match either the normal (“wild type”) ormutant configuration. Specifically, multiplex PCR has been used inconjunction with ASO hybridization in this dot blot format to screen 12CF mutations (Shuber et al., 1993). In several instances, arrays ofsubstrate-immobilized oligonucleotide probes were used to facilitate thedetection of known genomic DNA sequence variations (Saiki, R K et al.,1989) in a “reverse dot blot” format An array of short oligonucleotidessynthesized in-situ by photolithographicprocesses was used to detectknown mutations in the coding region of the CFTR gene (Cronin, M T., etal., 1996). Primer extension using reverse transcriptase has beenreported as a method for detecting the Δ508 mutation in CFTR (Pastinen,T., 2000). This approach was described as early as 1989 (Wu, D. Y. etal, Proc. Natl. Acad. Sci. USA. 86:2757-2760 (1989), Newton, C. R. etal, Nucleic Acids Res. 17:2503-2506 (1989)). As further discussed hereinbelow, while providing reasonable detection in a research laboratorysetting, these methods require significant labor, provide only slowturnaround, offer only low sample throughput, and hence require a highcost per sample.

In connection with the spotted microarrays, several methods of spottinghave been described, along with many substrate materials and methods ofprobe immobilization. However, the spotted arrays of current methodsexhibit not only significant array-to-array variability but alsosignificant spot-to-spot variability, an aspect that leads tolimitations in assay reliability and sensitivity. In addition, spottedarrays are difficult to miniaturize beyond their current spot dimensionsof typically 100 μm diameter on 500 μm centers, thereby increasing totalsample volumes and contributing to slow assay kinetics limiting theperformance of hybridization assays whose completion on spotted arraysmay require as much as 18 hours. Further, use of spotted arrays involvereadout via highly specialized confocal laser scanning apparatus. In analternative approach, oligonucleotide arrays synthesized in-situ by aphotolithographic process have been described. The complexity of arrayfabrication, however, limits routine customization and combinesconsiderable expense with lack of flexibility for diagnosticapplications.

The major histocompatibility complex (MHC) includes the human leukocyteantigen (HLA) gene complex, located on the short arm of human chromosomesix. This region encodes cell-surface proteins which regulate thecell-cell interactions underlying immune response. The various HLA ClassI loci encode 44,000 dalton polypeptides which associate with (3-2microglobulin at the cell surface and mediate the recognition of targetcells by cytotoxic T lymphocytes. HLA Class II loci encode cell surfaceheterodimers, composed of a 29,000 dalton and a 34,000 daltonpolypeptide which mediate the recognition of target cells by helper Tlymphocytes. HLA antigens, by presenting foreign pathogenic peptides toT-cells in the context of a “self” protein, mediate the initiation of animmune response. Consequently, a large repertoire of peptides isdesirable because it increases the immune response potential of thehost. On the other hand, the correspondingly high degree ofimmunogenetic polymorphism represents significant difficulties inallotransplantation, with a mismatch in HLA loci representing one of themain causes of allograft rejection. The degree of allele matching in theHLA loci of a donor and prospective recipient is a major factor in thesuccess of allogeneic tissue and bone marrow transplantation.

The HLA-A, HLA-B, and HLA-C loci of the HLA Class I region as well asthe HLA-DRB, HLA-DQB, HLA-DQA, HLA-DPB and HLA-DPA loci of the HLA ClassII region exhibit an extremely high degree of polymorphism. To date, theWHO nomenclature committee for factors of the HLA system has designated225 alleles of HLA A (HLA A*0101, A*0201, etc.), 444 alleles of HLA-B,and 111 alleles of HLA-C, 358 HLA-DRB alleles, 22 HLA-DQA alleles, 47HLA-DQB alleles, 20 HLA-DPA alleles and 96 HLA-DPB alleles (See IMGT/HLASequence Database, http://www3.ebi.ac.uk:80/imgt/hla/index.html) andSchreuder, G. M. Th. et al, Tissue Antigens. 54:409-437 (1999)), both ofwhich are hereby incorporated by reference.

HLA typing is a routine procedure that is used to determine theimmunogenetic profile of transplant donors. The objective of HLA typingis the determination of the patient's allele configuration at therequisite level of resolution, based on the analysis of a set ofdesignated polymorphisms within the genetic locus of interest.Increasingly, molecular typing of HLA is the method of choice overtraditional serological typing, because it eliminates the requirementfor viable cells, offers higher allelic resolution, and extends HLAtyping to Class II for which serology has not been adequate (Erlich, H.A. et al, Immunity. 14:347-356 (2001)).

One method currently applied to clinical HLA typing uses the polymerasechain reaction (PCR) in conjunction with sequence-specificoligonucleotide probes (SSO or SSOP), which are allowed to hybridize toamplified target sequences to produce a pattern as a basis for HLAtyping.

The availability of sequence information for all available HLA alleleshas permitted the design of sequence-specific oligonucleotides (SSO) andallele-specific oligonucleotides (ASO) for the characterization of knownHLA polymorphisms as well as for sequencing by hybridization (Saiki, R.K. Nature 324:163-166 (1986), Cao, K. et al, Rev Immunogenetics,1999:1:177-208).

In one embodiment of SSO analysis, also referred to as a “dot blotformat”, DNA samples are extracted from patients, amplified and blottedonto a set of nylon membranes in an 8×12 grid format. One radio-labeledoligonucleotide probe is added to each spot on each such membrane;following hybridization, spots are inspected by autoradiography andscored either positive (1) or negative (O). For each patient sample, thestring of 1's and 0's constructed from the analysis of all membranesdefines the allele configuration. A multiplexed format of SSO analysisin the “reverse dot blot format” employs sets of oligonucleotide probesimmobilized on planar supports (Saiki, R. et al, Immunological Rev. 167:193-199 (1989), Erlich, H. A. Eur. J. Immunogenet. 18: 33-55 (1991)).

Another method of HLA typing uses the polymerase-catalyzed elongation ofsequence-specific primers (SSPs) to discriminate between alleles. Thehigh specificity of DNA polymerase generally endows this method withsuperior specificity. In the SSP method, PCR amplification is performedwith a specific primer pair for each polymorphic sequence motif or pairof motifs and a DNA polymerase lacking 3′->5′ exonuclease activity sothat elongation (and hence amplification) occurs only for that primerwhose 3′ terminus is perfectly complementary (“matched”) to thetemplate. The presence of the corresponding PCR product is ascertainedby gel electrophoretic analysis. An example of a highly polymorphiclocus is the 280 nt DNA fragment of the HLA class II DR gene whichfeatures a high incidence of polymorphisms HLA typing based on the useof sequence-specific probes (SSP), also referred to as phototyping(Dupont, B. Tissue Antigen. 46: 353-354 (1995)), has been developed as acommercial technology that is in routine use for class I and class IItyping (Bunce, M. et al, Tissue Antigens. 46:355-367 (1995), Krausa, P.and Browning, M. J., Tissue Antigens. 47: 237-244 (1996), Bunce, M. etal, Tissue Antigens. 45:81-90 (1995)). However, the requirement of theSSP methods of the prior art for extensive gel electrophoretic analysisfor individual detection of amplicons represents a significantimpediment to the implementation of multiplexed assay formats that canachieve high throughput. This disadvantage is overcome by the methods ofthe present invention.

In the context of elongation reactions, highly polymorphic loci and theeffect of non-designated polymorphic sites as interfering polymorphismswere not considered in previous applications, especially in multiplexedformat. Thus, there is a need to provide for methods, compositions andprocesses for the multiplexed analysis of polymorphic loci that wouldenable the detection of designated while accommodating the presence ofno-designated sites and without interference from such non-designatedsites.

SUMMARY OF THE INVENTION

The present invention provides methods and processes for the concurrentinterrogation of multiple designated polymorphic sites in the presenceof non-designated polymorphic sites and without interference from suchnon-designated sites. Sets of probes are provided which facilitate suchconcurrent interrogation. The present invention also provides methods,processes, and probes for the identification of polymorphisms of the HLAgene complex and the CFTR gene.

The specificity of methods of detection using probe extension orelongation is intrinsically superior to that of methods usinghybridization, particularly in a multiplexed format, because thediscrimination of sequence configurations no longer depends ondifferential hybridization but on the fidelity of enzymatic recognition.To date, the overwhelming majority of applications of enzyme-mediatedanalysis use single base probe extension. However, probe elongation, inanalogy to that used in the SSP method of HLA typing, offers severaladvantages for the multiplexed analysis of polymorphisms, as disclosedherein. Thus, single nucleotide as well as multi-nucleotidepolymorphisms are readily accommodated. The method, as described herein,is generally practiced with only single label detection, accommodatesconcurrent as well as consecutive interrogation of polymorphic loci andincorporates complexity in the probe design.

One aspect of this invention provides a method of concurrentdetermination of nucleotide composition at designated polymorphic siteslocated within one or more target nucleotide sequences. This methodcomprises the following steps: (a) providing one or more sets of probes,each probe capable of annealing to a subsequence of the one or moretarget nucleotide sequences located within a range of proximity to adesignated polymorphic site; (b) contacting the set of probes with theone or more target nucleotide sequences so as to permit formation ofhybridization complexes by placing an interrogation site within a probesequence in direct alignment with the designated polymorphic site; (c)for each hybridization complex, determining the presence of a match or amismatch between the interrogation site and a designated polymorphicsite; and (d) determining the composition of the designated polymorphicsite.

Another aspect of this invention is to provide a method ofsequence-specific amplification of assay signals produced in theanalysis of a nucleic acid sequence of interest in a biological sample.This method comprises the following steps: (a) providing a set ofimmobilized probes capable of forming a hybridization complex with thesequence of interest; (b) contacting said set of immobilized probes withthe biological sample containing the sequence of interest underconditions which permit the sequence of interest to anneal to at leastone of the immobilized probes to form a hybridization complex; (c)contacting the hybridization complex with a polymerase to allowelongation or extension of the probes contained within the hybridizationcomplex; (d) converting elongation or extension of the probes into anoptical signal; and (e) recording the optical signal from the set ofimmobilized probes in real time.

Yet another aspect of this invention is to provide a method of forming acovering probe set for the concurrent interrogation of a designatedpolymorphic site located in one or more target nucleic acid sequences.This method comprises the steps of: (a) determining the sequence of anelongation probe capable of alignment of the interrogation site of theprobe with a designated polymorphic site; (b) further determining acomplete set of degenerate probes to accommodate all non-designated aswell as non-selected designated polymorphic sites while maintainingalignment of the interrogation site of the probe with the designatedpolymorphic site; and (c) reducing the degree of degeneracy by removingall tolerated polymorphisms.

One aspect of this invention is to provide a method for identifyingpolymorphisms at one or more designated sites within a targetpolynucleotide sequence. This the method comprise the following steps:(a) providing one or more probes capable of interrogating saiddesignated sites; (b) assigning a value to each such designated sitewhile accommodating non-designated polymorphic sites located within arange of proximity to each such polymorphism.

Another aspect of this invention is to provide a method for determininga polymorphism at one or more designated sites in a targetpolynucleotide sequence. This method comprises providing a probe set forthe designated sites and grouping the probe set in different probesubsets according to the terminal elongation initiation of each probe.

Another aspect of this invention is to provide a method for theconcurrent interrogation of a multiplicity of polymorphic sitescomprising the step of conducting a multiplexed elongation assay byapplying one or more temperature cycles to achieve linear amplificationof such target.

Yet another aspect of this invention is to provide a method for theconcurrent interrogation of a multiplicity of polymorphic sites. Thismethod comprises the step of conducting a multiplexed elongation assayby applying a combination of annealing and elongation steps undertemperature-controlled conditions.

Another aspect of this invention is to provide a method of concurrentinterrogation of nucleotide composition at S polymorphic sites,P_(S):={c_(p)(s); 1≦s≦S} located within one or more contiguous targetsequences, said method assigning to each c_(p) one of a limited set ofpossible values by performing the following steps: (a) providing a setof designated immobilized oligonucleotide probes, also known aselongation probes, each probe capable of annealing in a preferredalignment to a subsequence of the target located proximal to adesignated polymorphic site, the preferred alignment placing aninterrogation site within the probe sequence in direct juxtaposition tothe designated polymorphic site, the probes further containing aterminal elongation initiation (TEI) region capable of initiating anelongation or extension reaction; (b) permitting the one or more targetsequences to anneal to the set of immobilized oligonucleotide probes soas form probe-target hybridization complexes; and (c) for eachprobe-target hybridization complex, calling a match or a mismatch incomposition between interrogation site and corresponding designatedpolymorphic site.

Other objects, features and advantages of the invention will be moreclearly understood when taken together with the following detaileddescription of an embodiment which will be understood as beingillustrative only.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is an illustration of probe sets designed to interrogatedesignated sites in HLA-DR and an internal control.

FIG. 1 b is an illustration of a staggered primer design.

FIG. 2 is an illustration of a modification of allele binding patternbased on tolerance effect.

FIG. 3 is an illustration of the use of linked primer structure toseparate the anchoring sequence and polymorphism detection sequence.

FIG. 4 shows simulated ambiguity in allele identification due to allelecombination.

FIG. 5 shows one method for decreasing the ambiguity in alleleidentification that arises from allele combination.

FIG. 6 is an illustration of a combination of hybridization andelongation.

FIG. 7 shows a model reaction using synthetic oligonucleotides astargets.

FIG. 8 shows results obtained using testing real patient sample in aneMAP format.

FIG. 9 shows results obtained from eMAP primer extension for DR locus.

FIG. 10 shows results obtained from eMAP for DR locus.

FIG. 11 shows results obtained from eMAP for A locus Exon 3.

FIG. 12 shows results obtained from eMAP SSP for A locus Exon 3 and isan example of tolerance for the non-designated polymorphism.

FIG. 13 is an illustration of bead immobilized probe elongation ofvariable mutant sites.

FIG. 14 is an illustration of PCR using primers immobilized on thesurface of beads.

FIG. 15 is an illustration of elongation of multiple probes usingcombined PCR products.

FIG. 16 is an illustration of results for probe elongation of amultiplexed CF mutation. FIG. 16 a is an illustration of probeelongation using a synthetic target. FIG. 16 b is an illustration ofprobe elongation using beads in a PCR reaction.

FIG. 17 is an illustration of one-step elongation withtemperature-controlled cycling results.

FIG. 18 is an illustration of primer elongation with labeled dNTP andthree other unlabeled dNTPs.

FIG. 19 is an illustration of primer elongation with labeled ddNTP andthree other unlabeled dNTPs.

FIG. 20 is an illustration of primer elongation, where four unlabeleddNTPs are used for elongation and the product is detected by a labeledoligonucleotide probe which hybridizes to the extended unlabeledproduct.

FIG. 21 is an illustration of a primer extension in which a labeledtarget and four unlabeled dNTPs are added. This illustration which showsthat only with the extended product can the labeled target be retainedwith the beads when high temperature is applied to the chip.

FIG. 22 is an illustration of linear amplification where sequencespecific probes are immobilized.

FIG. 23 is an illustration of the utilization of hairpin probes.

FIG. 24 is an illustration of applying this invention to the analysis ofcystic fibrosis and Ashkenazi Jewish disease mutations.

DETAILED DESCRIPTION OF THE INVENTION

This invention provides compositions, methods and designs for themultiplexed analysis of highly polymorphic loci; that is, loci featuringa high density of specific (“designated”) polymorphic sites, as well asinterfering non-designated polymorphic sites. The multiplexed analysisof such sites thus generally involves significant overlap in thesequences of probes directed to adjacent sites on the same target, suchthat probes designed for any specific or designated site generally alsowill cover neighboring polymorphic sites. The interference in theanalysis of important genes including CFTR and HLA has not beenaddressed in the prior art. To exemplify the methods of the methods ofthe invention, the HLA gene complex and the CFTR gene are analyzed.

The present invention provides compositions and methods for the parallelor multiplexed analysis of polymorphisms (“MAP”) in nucleic acidsequences displaying a high density of polymorphic sites. In a givennucleic acid sequence, each polymorphic site comprises a differencecomprising one or more nucleotides.

This invention provides methods and compositions for the concurrentinterrogation of an entire set of designated polymorphisms within anucleic acid sequence. This invention provides compositions, methods anddesigns to determine the composition at each such site and therebyprovide the requisite information to select, from the set of possibleconfigurations for the sequence of interest, the actual configuration ina given specific sample. The invention also serves to narrow the set ofpossible sequences in that sample. Accordingly, in certain embodiments,it will be useful or necessary to determine sequence composition byassigning to a designated site one of the possible values correspondingto nucleotide identity. In other embodiments, it will be sufficient todetermine the site composition to be either matching or non-matchingwith respect to a known reference sequence, as in the assignment of“wild-type” or “mutation” in the context mutation analysis. Thecapability of sequence determination thereby afforded is referred toherein as confirmatory sequencing or resequencing. In a preferredembodiment, the present invention provides elongation-mediatedmultiplexed analysis of polymorphisms (eMAP) of the Cystic FibrosisTransmembrane Conductance Regulator (CFTR) gene and for the HumanLeukocyte Antigen (HLA) gene complex.

The methods and compositions of this invention are useful for improvingthe reliability and accuracy of polymorphism analysis of target regionswhich contain polymorphic sites in addition to the polymorphic sitesdesignated for interrogation. These non-designated sites represent asource of interference in the analysis. Depending on the specific assayapplications, one or more probes of differing composition may bedesignated for the same polymorphic site, as elaborated in severalExamples provided herein. It is a specific objective of the presentinvention to provide compositions and methods for efficient, rapid andunambiguous analysis of polymorphisms in genes of interest. Thisanalysis is useful in molecular diagnostic assays, such as thosedesigned, for example, for genetic testing, carrier screening,genotyping or genetic profiling, identity testing, paternity testing andforensics.

Preparation of target sequences may be carried out using methods knownin the art. In a non-limiting example, a sample of cells or tissue isobtained from a patient. The nucleic acid regions containing targetsequences (e.g., Exons 2 and 3 of HLA) are then amplified using standardtechniques such as PCR (e.g., asymmetric PCR).

Probes for detecting polymorphic sites function as the point ofinitiation of a polymerase-catalyzed elongation reaction when thecomposition of a polymorphic site being analyzed is complementary(“matched”) to that of the aligned site in the probe. Generally, theprobes of the invention should be sufficiently long to avoid annealingto unrelated DNA target sequences. In certain embodiments, the length ofthe probe may be about 10 to 50 bases, more preferably about 15 to 25,and more preferably 18 to 20 bases. Probes may be immobilized on thesolid supports via linker moieties using methods and compositions wellknown in the art.

As used herein, the term “nucleic acid” or “oligonucleotide” refers todeoxyribonucleic acid or ribonucleic acid in a single or double-strandedform. The term also covers nucleic-acid like structures with syntheticbackbones. DNA backbone analogues include phosphodiester,phosphorothioate, phosphorodithioate, methylphosphonate,phosphoramidate, alkyl phosphotriester, sulfamate, 3′-thioacetal,methylene(methylimino), 3′-N-carbamate, morpholino carbamate, andpeptide nucleic acids (PNAs). See Oligonucleotides and Analogues, APractical Approach (Editor: F. Eckstein), IRL Press at Oxford UniversityPress (1991); Antisense Strategies, Annals of the New York Academy ofSciences, vol. 600, Eds.; Baserga and Denhardt (NYAS 1992); Milligan, J.Med. Chem., vol. 36, pp. 1923-1937; Antisense Research and Applications(1993, CRC Press). PNAs contain non-ionic backbones, such asN-2(2-aminoethyl) glycine units. Phosphorothioate linkages are describedin WO 97/03211; WO 96/39159; and Mata, Toxicol. Appl. Pharmacol. 144:189-197 (1997). Other synthetic backbones encompassed by the terminclude methyl-phosphonate linkages or alternating methylphosphonate andphosphodiester linkages (Strauss-Soukup, Biochemistry, 36: 8692-8698(1997), and benzylphosphonate linkages (Samstag, Antisense Nucleic AcidDrug Dev., 6: 153-156 (1996)). The term nucleic acid includes genes,cDNAs, and mRNAs.

As used herein, the term “hybridization” refers to the binding,duplexing, or hybridizing of a nucleic acid molecule preferentially to aparticular nucleotide sequence under stringent conditions. The term“stringent conditions” refers to conditions under which a probe willhybridize preferentially to the corresponding target sequence, and to alesser extent or not at all to other sequences. A “stringenthybridization” is sequence dependent, and is different under differentconditions. An extensive guide to the hybridization of nucleic acids maybe found in, e.g. Tijssen, Laboratory Techniques in Biochemistry andMolecular Biology, Elsevier, N.Y. (1993). Generally, highly stringenthybridization and wash conditions are selected to about 5° C. lower thanthe thermal melting point (T_(m)) for the specific sequence at a definedionic strength and pH. The T_(m), is the temperature (under definedionic strength and pH) at which 50% of the target sequence hybridizes toa perfectly matched probe. Very stringent conditions are selected byconducting the assay at a temperature set to be equal to the T_(m) for aparticular probe. An example of highly stringent wash condition is 0.15M NaCl at 72° C. for about 15 minutes. An example of stringent washconditions is a 0.2×SSC wash at 65° C. for 15 minutes. See Sambrook,Molecular Cloning: A Laboratory Manual (2^(nd) Ed), vol. 1-3 (1989).

As used herein, the term “designated site” is defined as a polymorphicsite of interest (i.e., a polymorphic site that one intends to identify)on a given nucleic acid. The term “non-designated site” refers to anypolymorphic site that co-exists with a designated site or sites on agiven nucleic acid but is not of interest.

As used herein, the term “correlated designated sites” refers topolymorphic sites with correlated occurrences. Typically, each member ofsuch a set of polymorphic sites must be identified in order to identifythe allele to which the set belongs.

As used herein, the term “selected designated site” refers to apolymorphic site of interest on a given nucleic acid that also overlapswith the 3′end of a probe sequence of this invention. A “non-selecteddesignated site” refers to a polymorphic site of interest that does notoverlap with a 3′ end of a probe sequence of this invention.

As used herein, an “interfering non-designated site” refers to anon-designated polymorphic site that is within 1-5 bases from the 3′ endof a probe sequence of this invention. A “non-interfering non-designatedsite” refers to a non-designated site that is greater than 5 bases fromthe 3′ end of a probe sequence of this invention. The non-interferingnon-designated site may be closer to the 5′ end of the probe sequencethan to the 3′ end.

In certain embodiments, the probes of this invention comprise a“terminal elongation initiation” region (also referred to as a “TEI”region) and a Duplex Anchoring (“DA”) region. The TEI region refers asection of the probe sequence, typically the three or four 3′ terminalpositions of the probe. The TEI region is designed to align with aportion of the target nucleic acid sequence at a designated polymorphicsite so as to initiate the polymerase-catalyzed elongation of the probe.The DA region, typically comprises the remaining positions within theprobe sequence and is preferably designed to align with a portion of thetarget sequence in a region located close (within 3-5 bases) to thedesignated polymorphism.

As used herein, the term a “close range of proximity” refers to adistance of between 1-5 bases along a given nucleic acid strand. A“range of proximity” refers to a distance within 1-10 bases along agiven nucleic acid strand. The term “range of tolerance” refers to thetotal number of mismatches in the TEI region of a probe hybridized to atarget sequence that still permits annealing and elongation of theprobe. Typically, more than 2 mismatches in the TEI region of ahybridized probe is beyond the range of tolerance.

The terms “microspheres”, “microparticles”, “beads”, and “particles” areherein used interchangeably. The composition of the beads includes, butis not limited to, plastics, ceramics, glass, polystyrene,methylstyrene, acrylic polymers, paramagnetic materials, thoria sol,carbon graphite, titanium dioxide, latex or cross-linked dextrans suchas sepharose, cellulose, nylon, cross-linked micelles and Teflon. See“Microsphere Detection Guide” from Bangs Laboratories, Fishers IN. Theparticles need not be spherical and may be porous. The bead sizes mayrange from nanometers (e.g., 100 nm) to millimeters (e.g., 1 mm), withbeads from about 0.2 micron to about 200 microns being preferred, morepreferably from about 0.5 to about 5 micron being particularlypreferred.

This invention provides for the concurrent interrogation of a set ofdesignated polymorphic sites within one or more target strands by firstannealing a set of immobilized sequence specific oligonucleotide probesto target nucleic acid strands and by probing the configuration ofdesignated polymorphic sites by way of polymerase-catalyzed elongationof the annealed set of immobilized sequence-specific oligonucleotideprobes. An elongation probe is designed to interrogate a designated siteby annealing to a sequence in a given target, thereby forming ahybridization complex (“duplex”). The probe's 3′ terminus is placed ator near the designated site within the target and polymerase-catalyzedprobe elongation is initiated if the 3′ terminal probe compositionmatches (i.e., is complementary to) that of the target at theinterrogation site. As described herein, the probe may be designed toanneal in a manner such that the designated site is within a range ofproximity of the 3′ terminus.

In one embodiment of the invention, two or more probes may be providedfor interrogation of a specific designated site. The probes are designedto take into account the possibility of polymorphisms or mutations atthe interrogation site and non-designated polymorphic sites within acertain range of proximity of the designated polymorphic site. In thiscontext, the term “polymorphism” refers to any variation in a nucleicacid sequence, while the term “mutation” refers to a sequence variationin a gene that is associated or believed to be associated with aphenotype. In a preferred embodiment, this multiplicity of probesequences contains at least one probe that matches the specific targetsequence in all positions within the range of proximity to ensureelongation.

In certain embodiments, the invention discloses compositions and methodsfor the parallel interrogation of S polymorphic sites selected from atarget sequence of length N by a set of L S oligonucleotide primers.

In accordance with the requirements of specific assay applications, oneor more probes of differing composition may be designated for the samepolymorphic site, as elaborated in several Examples provided herein.

Each designated probe is composed of a nucleotide sequence of length Mwhich contains an interrogation site (one that, upon hybridization,aligns with the polymorphic site being analyzed) at or near the 3′terminus. Although 3′ end is preferred, those within 3-4 bases from the3′ end may be used. The primer is immobilized on a solid phase carrier(may be linked via a linker sequence or other linker moiety) and isidentified by its association with that carrier. The probe sequence isdesigned to permit annealing of the primer with the target so as to forma hybridization complex between probe and target and to ensure thealignment of the interrogation site with the designated polymorphicsite, the preferred configuration providing an interrogation site at theprobe's 3′ terminus and alignment of the 3′ terminus with the designatedpolymorphic site. The step of interrogating the nucleotide compositionof the designated polymorphic site with a designated probe of giveninterrogation site composition assigns to that site one of two values,namely matched, numerically represented by 1, or non-matched,numerically represented by 0. In HLA molecular typing, the resultingbinary string of length L identifies an allele to a desired typingresolution.

In a preferred embodiment, the interrogation step uses the extension ofthe designated probe. This reaction, catalyzed by a polymerase, producesan extended hybridization complex by adding to the probe sequence one ormore nucleoside triphosphates in the order reflecting the sequence ofthe target sequence in the existing hybridization complex. In order forthis extension reaction to proceed, a designated primer of length M mustcontain a terminal extension initiation region of length M*≦M, hereinalso referred to as terminal extension initiation sequence (or TEIsequence), which contains the interrogation site. Extension proceeds ifthe composition of the designated interrogation site matches that of thedesignated polymorphic site.

Methods of the prior art of detecting successful extension have beendescribed which involve the use labeled deoxy nucleoside triphosphates(dNTPs) or dideoxy nucleoside triphosphates (ddNTPs). The presentinvention also discloses novel methods of providing optical signaturesfor detection of successful extension eliminating the need for labeleddNTPs or ddNTPs, an advantage arising from the reduction in theefficiency of available polymerases in accommodating labeled dNTPs orddNTPs.

However, the density of polymorphic sites in highly polymorphic lociconsidered in connection with the present invention makes it likely thatdesignated primers directed to selected polymorphic sites, whenannealing to the target subsequence proximal to the designatedpolymorphic site, will overlap adjacent polymorphic sites.

That is, an oligonucleotide probe, designed to interrogate theconfiguration of the target at one of the selected polymorphic sites,and constructed with sufficient length to ensure specificity and thermalstability in annealing to the correct target subsequence, will alignwith other nearby polymorphic sites. These interfering polymorphic sitesmay include the non-designated sites as well as non-selected designatedsites in the target sequence.

In a multiplexed SSP reaction carried out in solution, the partialoverlap between designated probes directed to nearby selectedpolymorphisms may lead to mutual competition between probes for the sametarget. The present invention significantly reduces this complication byway of probe immobilization.

As with multiplexed differential hybridization generally, the mismatchin one or more positions between a designated probe and target mayaffect the thermal stability of the hybridization complex. That is, anyset of annealing conditions applied to the entire reaction mixture mayproduce varying degrees of annealing between probe and target and mayaffect the outcome of the subsequent probe extension reaction, therebyintroducing ambiguities in the assay which may require subsequentresequencing.

Non-designated polymorphic sites located in immediate proximity to theinterrogation site near or at the 3′ terminus of the designated probeare particularly deleterious to the effectiveness of the probe's TEIsequence in initiating the extension reaction.

The power of currently available polymerase enzymes catalyzing theextension reaction to discriminate between a match and a mismatch incomposition between the interrogation site within the designated primerand the polymorphic site depends on the displacement of theinterrogation site from the primer's 3′ terminus, considering singlenucleotide as well as multiple nucleotide polymorphisms.

In a preferred embodiment yielding optimal discriminating power, theinterrogation site is provided at the probe's 3′ terminus. Given a probesequence of length M designated for a selected site s* in therepresentation P_(M(s*)):={c_(P(m)); 1≦m≦M}, the index m increasing inthe primer's 5′ to 3′ direction, this configuration provides foralignment of the designated site s* with position M in the probesequence; in the case of multiple nucleotide polymorphisms, positionsM-1 (for a dinucleotide polymorphism) and M-2 (for a trinucleotidepolymorphism), etc. also are implicated.

Under these circumstances as they are anticipated in the multiplexedanalysis of highly polymorphic loci, the advantage of enhancedspecificity afforded by the application of a polymerase-catalyzedextension reaction is greatly diminished or lost as a result ofcomplications arising from “sub-optimal” annealing conditions closelyrelated to those limiting the performance of SSO analysis.

In connection with the optimization of the design of multiple probesequences sharing the same interrogation site composition for any givendesignated polymorphic site, it will be useful to consider the conceptof tolerance of interfering polymorphisms. Considering withoutlimitation of generality the example of the single nucleotidepolymorphism, a shift in alignment of s* away from the 3′ terminus topositions M-1, M-2, . . . , M-m* leads to a gradually diminisheddiscriminatory power. That is, when the designated polymorphic site isaligned with an interior probe position, m*, the extension reaction nolonger discriminates between match and mismatch. Conversely, in thepreferred embodiment of placing the interrogation site at the probe's 3′terminus, the deleterious effect of nearby non-designated polymorphismson the effectiveness of the extension reaction likewise decreases withdistance from the 3′ terminus. That is, non-designated polymorphismsaligned with position between 1 and m* will not affect the extensionreaction.

The terminal sequence of length M-m*+1 within the probe is hereinreferred to as the TEI sequence of a given primer. In general, 1<m*<M,and the TEI sequence may comprise only small number of terminal probepositions; in certain cases, m*=1, so that the probe sequenceencompasses the entire probe sequence.

The present invention accommodates the presence of interferingpolymorphic sites within the length of a designated probe sequence bytaking into account these known sequence variations in the design ofmultiple probes. In particular, the number of alternate probe sequenceconfigurations to be provided for given probe length M is significantlyreduced as a result of the existence of a TEI sequence of length M-m*+1.That is, in order to ensure effective discriminatory power of theextension reaction, it is sufficient to restrict the anticipatoryalternate probe sequence configurations to the length of the TEIsequence. In a preferred embodiment, all possible alternative sequencesare anticipated so that one of these alternate probe sequences willmatch the target in all of the positions m*, m*+1, . . . M-1, M.

Providing, for each selected polymorphic site, a multiplicity ofdesignated probes with anticipatory sequences increases the complexityof coding if all of these probes are separately encoded by the uniqueassociation with coded solid phase carriers. However, this complexity isreduced by placing this set of probes on a common solid phase carrier.That is, only the interrogation site composition of any designatedprobes is encoded, a concept herein referred to as TEI sequence poolingor probe pooling. Complete probe sequence pooling reduces the codingcomplexity to that of the original design in which no anticipatory probesequences were provided. Partial pooling also is possible.

In certain preferred embodiments, the polymerase used in probeelongation is a DNA polymerase that lacks 3′ to 5′ exonuclease activity.Examples of such polymerases include T7 DNA polymerase, T4 DNApolymerase, ThermoSequenase and Taq polymerase. When the target nucleicacid sequence is RNA, reverse transcriptase may be used. In addition topolymerase, nucleoside triphosphates are added, preferably all fourbases. For example dNTPs, or analogues, may be added. In certain otherembodiments, ddNTPs may be added. Labeled nucleotide analogues, such asCyc3-dUTP may also be used to facilitate detection.

Prior art methods for detecting successful elongation have beendescribed which use labeled deoxy nucleoside triphosphates (dNTPs) ordideoxy nucleoside triphosphates (ddNTPs). This invention disclosesnovel methods of providing optical signatures for detecting successfulelongation, thus eliminating the need for labeled dNTPs or ddNTPs. Thisis advantageous because currently available polymerases are lessefficient in accommodating labeled dNTPs or ddNTPs.

This invention provides methods and compositions for accuratepolymorphism analysis of highly polymorphic target regions. As usedherein, highly polymorphic sequences are those containing, within aportion of the sequence contacted by the probe, not only the designatedor interrogated polymorphic site, but also non-designated polymorphicsites which represent a potential source of error in the analysis.Analogous considerations pertain to designs, compositions and methods ofmultiplexing PCR reactions. In a preferred embodiment, covering sets ofPCR probes composed of priming and annealing subsequences are displayedon encoded microparticles to produce bead-displayed amplicons by probeelongation. Assemblies of beads may be formed on planar substrates,prior to or subsequent to amplification to facilitate decoding andimaging of probes.

In one embodiment, this invention provides probes that are designed tocontain a 3′ terminal “priming” subsequence, also referred to herein asa Terminal Elongation Initiation (TEI) region, and an annealingsubsequence, also referred to herein as a Duplex Anchoring (DA) region.The TEI region typically comprises the three or four 3′ terminalpositions of a probe sequence. The TEI region is designed to align witha portion of the target sequence at a designated polymorphic site so asto initiate the polymerase-catalyzed elongation of the probe. Probeelongation indicates a perfect match in composition of the entire TEIregion and the corresponding portion of the target sequence. The DAregion, comprising remaining positions within the probe sequence, ispreferably designed to align with a portion of the target sequence in aregion located close (within 3-5 bases) to the designated polymorphism.The duplex anchoring region is designed to ensure specific and strongannealing, and is not designed for polymorphism analysis. As describedherein, the DA and TEI regions may be located immediately adjacent toone another within the probe or may be linked by a molecular tether. Thelatter approach permits flexibility in the placement of DA region so asto avoid non-designated polymorphisms located immediately adjacent tothe designated site. The composition and length of the DA region arechosen to facilitate the formation of a stable sequence-specifichybridization complex (“duplex”), while accommodating (i.e., taking intoaccount) the presence of one or more non-designated polymorphismslocated in that region of the target. The length of the annealingsubsequence is chosen to minimize cross-hybridization by minimizingsequence homologies between probe and non-selected subsequences of thetarget. The length of the annealing subsequence generally exceeds thatof the priming subsequence so that failure to form a duplex generallyimplies failure to produce an elongation product.

The elongation reaction provides high specificity in detectingpolymorphisms located within the TEI region. For non-designatedpolymorphisms in the DA region, the elongation reaction will proceed ata level either comparable to, or lower than that of the perfect matchunder certain conditions. This is referred to as the tolerance effect ofthe elongation reaction. Tolerance is utilized in the design of probesto analyze designated and non-designated polymorphisms as described inexamples herein.

The density of polymorphic sites in the highly polymorphic lociconsidered in certain embodiments of this invention makes it likely thatprobes directed to designated polymorphic sites will overlap adjacentpolymorphic sites, when annealing to a target subsequence proximal tothe designated polymorphic site. That is, an oligonucleotide probedesigned to interrogate the configuration of the target at a selecteddesignated polymorphic site, and constructed with sufficient length toensure specificity and thermal stability in annealing to the correcttarget subsequence will align with nearby polymorphic sites. Theseinterfering polymorphic sites may include non-designated sites in thetarget sequence as well as designated but not selected polymorphic sites

Specifically, non-designated polymorphisms as contemplated in thepresent invention may interfere with duplex formation, therebyinterfering with or completely inhibiting probe elongation. In oneembodiment, the present invention provides designs of covering probesets to accommodate such non-designated polymorphisms. A covering probeset contains probes for concurrently interrogating a given multiplicityof designated polymorphic sites within a nucleic acid sequence. Acovering probe set comprises, for each site, at least one probe capableof annealing to the target so as to permit, on the basis of a subsequentelongation reaction, assignment of one of two possible values to thatsite: “matched” (elongation) or “unmatched”, (no elongation).

The covering probe set associated with each designated site may containtwo or more probes differing in one or more positions, also referred toherein as a degenerate set. In certain embodiments, the probe sequencemay contain universal nucleotides capable of forming a base-pair withany of the nucleotides encountered in DNA. In certain embodiments,probes may be attached to encoded microparticles, and specifically, twoor more of the probes in a covering set or degenerate set may beattached to the same type of microparticle. The process of attaching twoor more probes to a microparticle or bead is referred to as “probepooling”.

The design of covering probe sets is described herein in connection withelongation-mediated multiplexed analysis of polymorphisms in tworepresentative areas of genetic analysis: (1): the scoring of multipleuncorrelated designated polymorphisms and mutations, as in the case ofmutation analysis for CF and Ashkenazi Jewish (AJ) disease carrierscreening, and (2) the scoring of a correlated set of polymorphisms asin the case of HLA molecular typing. In the first instance, the coveringset for the entire multiplicity of mutations contains multiple subsets,each subset being associated with one designated site. In such a case,two or more probes are provided to ascertain heterozygosity. For thepurpose of general SNP identification and confirmatory sequencing,degenerate probe sets can be provided to contain up to four labeled(e.g., bead-displayed) probes per polymorphic site. In the secondinstance, the covering set contains subsets constructed to minimize thenumber of probes in the set, as elaborated herein. The set of designatedprobes is designed to identify allele-specific sequence configurationson the basis of the elongation pattern.

While this method of accommodating or identifying non-designatedpolymorphic sites is especially useful in connection with themultiplexed elongation of sequence specific probes, it also may be usedin conjunction with single base extension of probes, also known asmini-sequencing (see e.g., Pastinen, et al. Genome Res. 7: 606-614(1997), incorporated herein by reference).

The elongation-mediated method of analysis of the present invention,unlike the single-base probe extension method, may be used to detect notonly SNPs, but also to detect other types of polymorphisms such asmultiple (e.g., double, triple, etc.) nucleotide polymorphisms, as wellas insertions and deletions commonly observed in the typing of highlypolymorphic genetic loci such as HLA. In these complex systems,sequence-specific probe elongation in accordance with the methods ofthis invention, simplifies the detection step because two or more probesare provided for each polymorphic target location of interest and thedetection step is performed only to determine which of the two or moreprobes was elongated, rather than to distinguish between two extendedprobes, as in the case of single-base probe extension Thus, although themethods of this invention accommodate the use of multiple fluorophore orchromophore labels in the detection step, a single universal labelgenerally will suffice for the sequence specific probe elongation. Thisis in contrast to single-base extension methods whose application in amultiplexed format requires at least two fluorophore or chromophorelabels.

DNA methylation: In certain embodiments, methods and compositions fordetermining the methylation status of DNA are provided. Cytosinemethylation has long been recognized as an important factor in thesilencing of genes in mammalian cells. Cytosine methylation at singleCpG dinucleotides within the recognition sites of a number oftranscription factors is enough to block binding and related to severaldiseases. eMAP can be used to determine the methylation status ofgenomic DNA for diagnostic and other purposes. The DNA is modified bysodium bisulfite treatment converting unmethylated Cytosines to Uracil.Following removal of bisulfite and completion of the chemicalconversion, this modified DNA is used as a template for PCR. A pair ofprobes is designed, one specific for DNA that was originally methylatedfor the gene of interest, and one specific for unmethylated DNA. eMAP isperformed with DNA polymerase and one labeled dNTP and unlabeled mixtureof 3 dNTPs or ddNTPs. The elongated product on the specific bead surfacecan indicate the methylation status.

Selective Sequencing: In certain other embodiments of this invention,selective sequencing (also referred to as “sequencing”) is used forconcurrent interrogation of an entire set of designated polymorphismswithin a nucleic acid sequence in order to determine the composition ateach such site. Selective sequencing can be used to provide therequisite information to select, from the set of possible configurationsfor the sequence of interest, the actual configuration in a givenspecific sample or to narrow the set of possible sequences in thatsample. In selective sequencing, the length of probes used in anextension reaction determine the length of the sequences that can bedetermined. For longer DNA sequences, staggered probe designs can beused to link the sequences together. Thus, known sequence combinationscan be confirmed, while unknown sequence combinations can be identifiedas new alleles.

Cystic Fibrosis Carrier Screening—One practical application of thisinvention involves the analysis of a set of designated mutations withinthe context of a large set of non-designated mutations and polymorphismsin the Cystic Fibrosis Transmembrane Conductance (CFTR) gene. Each ofthe designated mutations in the set is associated with the disease andmust be independently scored. In the simplest case of a point mutation,two encoded probes are provided to ensure alignment of their respective3′ termini with the designated site, with one probe anticipating thewild-type, and the other anticipating the altered (“mutated”) targetsequence.

However, to ensure elongation regardless of the specific target sequenceconfiguration encountered near the designated site, additional probesare provided to match any of the possible or likely configurations, asdescribed in several Example herein. In a preferred embodiment, thecovering probe set is constructed to contain probes displaying TEIsequences corresponding to all known or likely variations of thecorresponding target subsequence. This ensures elongation in thepresence of otherwise elongation-inhibiting non-designated polymorphismslocated within a range of proximity of the designated site.

In certain embodiments, the identification of the specific targetconfiguration encountered in the non-designated sites is not necessaryso long as one of the sequences provided in the covering probe setmatches the target sequence sufficiently closely to ensure elongation,and thus matches the target sequence exactly within the TEI region. Inthis case, all or some of the covering probes sharing the same 3′terminus may be assigned the same code In a preferred embodiment, suchprobes may be associated with the same solid support (“probe pooling”).Probe pooling reduces the number of distinguishable solid supportsrequired to represent the requisite number of TEI sequences. In oneparticularly preferred embodiment, solid supports are provided in theform of a set or array of distinguishable microparticles which may bedecoded in-situ. Inclusion of additional probes in the covering probeset to identify additional polymorphisms in the target region is auseful method to elucidate haplotypes for various populations.

HLA—Another application of this invention involves the genetic analysisof the Human Leukocyte Antigen (HLA) complex, allowing theidentification of one or more alleles within regions of HLA encodingclass I HLA antigens (preferably HLA-A, HLA-B, HLA-C or any combinationthereof) and class II HLA antigens (preferably including HLA-DR, HLA-DQ,HLA-DP or any combination thereof). Class I and II gene loci also may beanalyzed simultaneously.

In contrast to the independent scoring of multiple uncorrelateddesignated mutations, identification of alleles (or groups of alleles)relies on the scoring of an entire set of elongation reactions. Each ofthese reactions involves one or more probes directed to a member of aselected set of designated polymorphic sites. The set of theseelongation reactions produces a characteristic elongation signalpattern. In a preferred embodiment, a binary pattern is produced,assigning a value of “1” to matching (and hence elongated) probes, and avalue of “0” to non-elongated probes. The binary pattern (“string”) ofgiven length uniquely identifies an allele or a group of alleles.

The total number of probes required for HLA typing depends on thedesired resolution. The term “resolution” is used here to indicate thedegree of allelic discrimination. Preferably, the method of thisinvention allows typing of an HLA allele that is sufficient todistinguish different antigen groups. For example, A*01 and A*03 aredifferent antigen groups that have to be distinguished in clinicalapplications. The National Marrow Donor Program (NMDP) recommended apanel for molecular typing of the donors. The low-to-medium resolutionrequired by the NMDP panel means that different antigen groups should bedistinguished at all times. Further, at least some of the alleles withinone group should be distinguished, though not necessarily all alleles.In certain embodiments, the present invention allows typing of the HLAallele to a low to medium resolution, as defined by the NMDP standard(www.NMDPresearch.org), incorporated herein by reference.

With such resolution, A*01, A*03 etc., will always be identified. A*0101and A*0102 may not be necessarily distinguishable. For the SSO method,the current NMDP panel contains 30 probes for HLA-A; 48 for HLA-B and 31for HLA-DR-B. High resolution HLA typing refers to the situation whenmost of the alleles will be identified within each group. In this case,A*0101 and A*0102 will be distinguished. To reach such resolution,approximately 500 to 1000 probes will be required for both class I andclass II typing. In certain embodiments, the method of the presentinvention provides high resolution HLA typing, at least to the degreedescribed in Cao, et al., Rev. Immunogentics, 1: 177-208 (1999),incorporated herein by reference.

This invention also provides strategies for designating sites and fordesigning probe sets for such designated sites in order to produceunique allele assignments based on the elongation reaction signalpatterns. The design of covering probes explicitly takes into accountthe distinct respective functions of TEI and DA regions of each probe.

A covering set of probes associated with a given designated site isconstructed to contain subsets. Each subset in turn contains probesdisplaying identical TEI regions. A mismatch in a single position withinthe TEI region, or a mismatch in three or more positions within the DAregion precludes elongation. Accordingly, the elongation of two probesdisplaying such differences in composition generally will producedistinct elongation patterns. All such probes can be multiplexed in aparallel elongation reaction as long as they are individually encoded.In a preferred embodiment, encoding is accomplished by attaching probesto color-encoded beads.

Probes displaying identical TEI subsequences and displaying DAsubsequences differing in not more than two positions generally willproduce elongation reactions at a yield (and hence signal intensity)either comparable to, or lower than that of a perfect match. In thefirst case which indicates tolerance of the mismatch, the set of allelesmatched by the probe in question will be expanded to include allelesthat display the tolerated mismatched sequence configurations within theDA region. In the second case, indicating only partial tolerance, threeapproaches are described herein to further elucidate the allele matchingpattern. In the first approach, probes displaying one or two nucleotidepolymorphisms in their respective DA regions are included in thecovering set. Information regarding the target sequence is obtained byquantitatively comparing the signal intensities produced by thedifferent probes within the covering set. In the second approach, probescomprising separate TEI and DA regions joined by a tether are used toplace the DA region farther away from the TEI region in order to avoidtarget polymorphisms. In the third approach, probes are optionallypooled in such cases offering only a modest expansion of the set ofmatched alleles.

In certain embodiments of this invention probes preferably are designedto be complementary to certain target sequences that are known tocorrelate with allele combinations within the HLA gene locus. Knownpolymorphisms are those that have appeared in the literature or areavailable from a searchable database of sequences (e.g.,www.NMDProcessing.org). In certain embodiments, the HLA gene of interestbelongs to HLA class I group, (e.g., HLA-A, HLA-B or HLA-C orcombination thereof). In certain other embodiments, the HLA gene ofinterest belongs to the HLA class II group, (e.g., DR, DQ, DP orcombination thereof). The HLA class I and class II loci may be examinedin combination and by way of concurrent interrogation.

Probes previously employed in the SSP/gel method also may be used inthis invention. Preferably, the probes set forth in Bunce et al., TissueAntigen, 46: 355-367 (1995) and/or Bunce et al., Tissue Antigen,45:81-90 (1995), (each of which are hereby incorporated by reference)are used in preparing the probes for this invention. The probe sequencesor HLA sequence information provided in WO 00/65088; EuropeanApplication No. 98111696.5; WO 00/70006; and Erlich et al., Immunity,14: 347-356 (2001), (each of which are hereby incorporated by reference)may be used in designing the probes for this invention.

The complexity of an encoded bead array is readily adjusted toaccommodate the requisite typing resolution. For example, when 32 typesof beads are used for each of four distinct subarrays, a total of 128probes will be available to attain a medium level of resolution for HLAclass I and class II typing in a multiplexed elongation reaction.Analogously, with 128 types of beads and four subarrays, or 64 types ofbeads and 8 subarrays, a total of 512 probes will be available to attaina high resolution of HLA class I and class II typing in a multiplexedelongation reaction.

The encoded bead array format is compatible with high throughputanalysis. For example, certain embodiments of this invention provide acarrier that accommodates multiple samples in a format that iscompatible with the dimensions of 96-well microplates, so that sampledistribution may be handled by a standard robotic fluid handlingapparatus. This format can accommodate multiple encoded bead arraysmounted on chips and permits the simultaneous completion of multipletyping reactions for each of multiple patient samples on a singlemulti-chip carrier In a 96-well carrier testing 128 types per patient,more than 10,000 genotypes can be determined at a rate of throughputthat is not attainable by current SSP or SSO methodology.

In certain embodiments of this invention, the elongation reaction can becombined with a subsequent hybridization reaction to correlatesubsequences on the same DNA target strand, a capability referred toherein as “phasing”. Phasing resolves ambiguities in allele assignmentarising from the possibility that a given elongation pattern isgenerated by different combinations of alleles. Similarly, phasing isuseful in the context of haplotying to assign polymorphisms to the sameDNA strand or chromosome.

In certain embodiments of this invention, the annealing and elongationsteps of the elongation reaction can be combined as a one-step reaction.Furthermore, means to create continuous or discrete temperaturevariations can be incorporated into the system to accommodate multipleoptimal conditions for probes with different melting temperatures in amultiplexed reaction.

In certain embodiments of this invention, encoded bead arrays are formedon solid substrates. These solid substrates may comprise any suitablesolid material, such as glass or semiconductor, that has sufficientmechanical strength and can be subjected to fabrication steps, ifdesired. In some embodiments, the solid substrates are divided intodiscrete units known as “chips”. Chips comprising encoded bead arraysmay be processed individually or in groups, if they are loaded into amultichip carrier. For example, standard methods of temperature controlare readily applied to set the operating temperature of, or to apply apreprogrammed sequence of temperature changes to, single chips or tomultichip carriers. Further, chips may be analyzed with the directimaging capability of Random Encoded Array Detection (“READ”), asdisclosed in PCT/US01/20179, the contents of which are incorporatedherein by reference. Using READ, the multiplexed analysis of entirearrays of encoded beads on chips is possible. Furthermore, in the READformat, the application of preprogrammed temperature cycles providesreal-time on-chip amplification of elongation products. Given genomic,mitochondrial or other DNA, linear on-chip amplification may obviate theneed for pre-assay DNA amplification such as PCR, thereby dramaticallyshortening the time required to complete the entire typing assay.Time-sensitive applications such as cadaver typing are thereforepossible. More importantly, this approach eliminates the complexities ofPCR multiplexing, which is a limiting step in many genetic screening andpolymorphism analyses. In a preferred embodiment, a fluidic cartridgeprovides for sample and reagent injection as well as temperaturecontrol.

In one embodiment, the invention provides a method for polymorphismanalysis in which each target nucleic acid sequence is used as atemplate in multiple elongation reactions by applying one or more“annealing-extending-detecting-denaturing” temperature cycles. Thismethod achieves linear amplification with in-situ detection of theelongation products. This additional capability obviates the need for afirst step of sequence-specific amplification of a polynucleotide sampleIntegration of assay procedure and signal amplification by way ofcycling not only simplifies and accelerates the completion of geneticanalysis, but also eliminates the need to develop, test and implementmultiplexed PCR procedures. The methods of this invention also provide ahigh-throughput format for the simultaneous genetic analysis of multiplepatient samples.

Several embodiments of this invention are provided for the multiplexedelongation of sequence-specific probes to permit simultaneous evaluationof a number of different targets. In certain embodiments,oligonucleotide probes are immobilized on a solid support to createdense patterns of probes on a single surface, e.g., silicon or glasssurface. In certain embodiments, presynthesized oligonucleotide probesare immobilized on a solid support, examples of which include silicon,chemically modified silicon, glass, chemically modified glass orplastic. These solid supports may be in the form of microscopic beads.The resolution of the oligonucleotide array is determined by bothspatial resolution of the delivery system and the physical spacerequirements of the delivered nucleotide solution volume. [See Guo, etal., Nucleic Acids Res. 22: 5456-5465 (1994); Fahy, et al., Nucleic AcidRes. 21: 1819-1826 (1993); Wolf, et al., Nuc. Acids Res. 15: 2911-2926(1987); and Ghosh, et al., Nuc. Acids Res. 15: 5353-5372 (1987).]

This invention provides methods for multiplexed assays. In certainembodiments, sets of elongation probes are immobilized on a solid phasein a way that preserves their identity, e.g., by spatially separatingdifferent probes and/or by chemically encoding the probe identities. Oneor more solution-borne targets are then allowed to contact amultiplicity of immobilized probes in the annealing and elongationreactions. This spatial separation of probes from one another byimmobilization reduces ambiguities in identifying elongation products.Thus, this invention offers advantages over the existing PCR-SSP method,which is not adaptable to a high throughput format because of (i) itsrequirement for two probes for each PCR amplification; (ii) thecompetition between overlapping probes for the highly polymorphic genes,such as HLA, in a multiplexed homogeneous reaction; and (iii) thedifficulty in distinguishing between specific products in such amultiplexed reaction.

In a preferred embodiment, probes are attached, via their respective 5′termini, to encoded microparticles (“beads”) having a chemically orphysically distinguishable characteristic that uniquely identifies theattached probe. Probes capture target sequences of interest contained ina solution that contacts the beads. Elongation of the probe displayed ona particular bead produces an optically detectable signature or achemical signature that may be converted into an optically detectablesignature. In a multiplexed elongation reaction, the optical signatureof each participating bead uniquely corresponds to the probe displayedon that bead. Subsequent to the probe elongation step, one may determinethe identity of the probes by way of particle identification anddetection, e.g., by flow cytometry.

In certain embodiments, beads may be arranged in a planar array on asubstrate before the elongation step. Beads also may be assembled on aplanar substrate to facilitate imaging after the elongation step. Theprocess and system described herein provide a high throughput assayformat permitting the instant imaging of an entire array of beads andthe simultaneous genetic analysis of multiple patient samples.

The array of beads may be a random encoded array, in which a chemicallyor physically distinguishable characteristic of the beads within thearray indicates the identity of oligonucleotide probes attached to thebeads. The array may be formed according to the READ format The beadarray may be prepared by employing separate batch processes to produceapplication-specific substrates (e.g., a chip at the wafer scale). Beadsthat are encoded and attached to oligonucleotide probes (e.g., at thescale of about 10⁸ beads/100 μl suspension) are combined with asubstrate (e.g., silicon chip) and assembled to form dense arrays on adesignated area of the substrate. In certain embodiments, the bead arraycontains 4000 beads of 3.2 μm diameter and has a dimension of 300 μm by300 μm. With beads of different size, the density will vary. Multiplebead arrays also can be formed simultaneously in discrete fluidcompartments maintained on the same chip. Such methods are disclosed inU.S. application Ser. No. 10/192,351, filed Jul. 9, 2002, which isincorporated herein by reference in its entirety.

Bead arrays may be formed by the methods collectively referred to as“LEAPS”, as described in U.S. Pat. No. 6,251,691 and PCT InternationalApplication No. PCT/US00/25466), both of which are incorporated hereinby reference.

The substrate (e.g., a chip) used in this invention may be in the formof a planar electrode patterned in accordance with the interfacialpatterning methods of LEAPS. For example, the substrate may be patternedwith oxide or other dielectric materials to create a desiredconfiguration of impedance gradients in the presence of an applied ACelectric field. Patterns may be designed so as to produce a desiredconfiguration of AC field-induced fluid flow and corresponding particletransport. Substrates may be patterned on a wafer scale by usingsemiconductor processing technology. In addition, substrates may becompartmentalized by depositing a thin film of a UV-patternable,optically transparent polymer to affix to the substrate a desired layoutof fluidic conduits and compartments. These conduits and compartmentsconfine fluid in one or several discrete compartments, therebyaccommodating multiple samples on a given substrate.

Bead arrays may be prepared using LEAPS by providing a first planarelectrode that is in substantially parallel to a second planar electrode(“sandwich” configuration) with the two electrodes being separated by agap and containing a polarizable liquid medium, such as an electrolytesolution. The surface or the interior of the second planar electrode maybe patterned with the interfacial patterning method. The beads areintroduced into the gap. When an AC voltage is applied to the gap, thebeads form a random encoded array on the second electrode (e.g., a“chip”).

In another embodiment of LEAPS, an array of beads may be formed on alight-sensitive electrode (e.g., a “chip”). Preferably, the sandwichconfiguration described above is also used with a planar light sensitiveelectrode and another planar electrode. Once again, the two electrodesare separated by the a gap and contain an electrolyte solution. Thefunctionalized and encoded beads are introduced into the gap. Uponapplication of an AC voltage in combination with light, the beads forman array on the light-sensitive electrode.

In certain embodiments of the present invention, beads may be associatedwith a chemically or physically distinguishable characteristic. This maybe provided, for example, by staining beads with sets of opticallydistinguishable tags, such as those containing one or more fluorophoreor chromophore dyes spectrally distinguishable by excitation wavelength,emission wavelength, excited-state lifetime or emission intensity. Theoptically distinguishable tags may be used to stain beads in specifiedratios, as disclosed, for example, in Fulwyler, U.S. Pat. No. 4,717,655(Jan. 5, 1988). Staining may also be accomplished by swelling ofparticles in accordance with methods known to those skilled in the art,(Molday, Dreyer, Rembaum & Yen, J. Mol. Biol 64, 75-88 (1975); L. Bangs,“Uniform latex Particles, Seragen Diagnostics, 1984). For example, up totwelve types of beads were encoded by swelling and bulk staining withtwo colors, each individually in four intensity levels, and mixed infour nominal molar ratios. Alternatively, the methods of combinatorialcolor encoding described in International Application No. PCT/US98/10719 (incorporated by reference in its entirety) can be used toendow the bead arrays with optically distinguishable tags. In additionto chemical encoding, beads may also be rendered magnetic by theprocesses described in PCT/US0/20179.

In addition to chemical encoding with dyes, beads having certainoligonucleotide primers may be spatially separated (“spatial encoding”),such that the location of the beads provides information as to theidentity of the beads. Spatial encoding, for example, can beaccomplished within a single fluid phase in the course of array assemblyby using Light-controlled Electrokinetic Assembly of Particles nearSurfaces (LEAPS). LEAPS can be used to assemble planar bead arrays inany desired configuration in response to alternating electric fieldsand/or in accordance with patterns of light projected onto thesubstrate.

LEAPS can be used to create lateral gradients in the impedance at theinterface between a silicon chip and a solution to modulate theelectrohydrodynamic forces that mediate array assembly. Electricalrequirements are modest: low AC voltages of typically less than 10V_(pp)are applied across a fluid gap between two planar electrodes that istypically 100 μm. This assembly process is rapid and it is opticallyprogrammable: arrays containing thousands of beads are formed withinseconds under an applied electric field. The formation of multiplesubarrays can also occur in multiple fluid phases maintained on acompartmentalized chip surface.

Subsequent to the formation of an array, the array may be immobilized.For example, the bead arrays may be immobilized, for example, byapplication of a DC voltage to produce random encoded arrays. The DCvoltage, set to typically 5-7 V (for beads in the range of 2-6 μm andfor a gap size of 100-150 μm) and applied for <30 s in “reverse bias”configuration so that an n-doped silicon substrate would form the anode,causes the array to be compressed to an extent facilitating contactbetween adjacent beads within the array and simultaneously causes beadsto be moved toward the region of high electric field in immediateproximity of the electrode surface. Once in sufficiently closeproximity, beads are anchored by van der Waals forces mediating physicaladsorption. This adsorption process is facilitated by providing on thebead surface a population of “tethers” extending from the bead surface;polylysine and streptavidin have been used for this purpose.

In certain embodiments, the particle arrays may be immobilized bychemical means, e.g, by forming a composite gel-particle film. In oneexemplary method for forming such gel-composite particle films, asuspension of microparticles is provided which also contains monomer,crosslinker and initiator for in-situ gel formation. The particles areassembled into a planar assembly on a substrate by using LEAPS. ACvoltages of 1-20 V_(p-p) in a frequency range from 100's of hertz toseveral kilohertz are applied between the electrodes across the fluidgap. In the presence of the applied AC voltage, polymerization of thefluid phase is triggered after array assembly by thermally heating thecell to ˜40-45° C. using an infra-red (IR) lamp or photoinitiating thereaction using a mercury lamp source. The resultant gel effectivelyentraps the particle array. Gels may be composed of a mixture ofacrylamide and bisacrylamide of varying monomer concentrations from 20%to 5% (acrylamide:bisacrylamide=37.5:1, molar ratio), but any other lowviscosity water soluble monomer or monomer mixture may be used as well.Chemically immobilized functionalized microparticle arrays prepared bythis process may be used for a variety of bioassays, e.g., ligandreceptor binding assays.

In one example, thermal hydrogels are formed using azodiisobutyramidinedihydrochloride as a thermal initiator at a low concentration to ensurethat the overall ionic strength of the polymerization mixture falls inthe range of ˜0.1 mM to 1.0 mM. The initiator used for the UVpolymerization is Irgacure 2959®(2-Hydroxy-4′-hydroxyethoxy-2-methylpropiophenone, Ciba Geigy,Tarrytown, N.Y.). The initiator is added to the monomer to give a 1.5%by weight solution.

In certain embodiments, the particle arrays may be immobilized bymechanical means. For example, an array of microwells may be produced bystandard semiconductor processing methods in the low impedance regionsof a silicon substrate. Particle arrays may be formed using suchstructures. In certain embodiments LEAPS mediated hydrodynamic andponderomotive forces are utilized to transport and to accumulateparticles on the hole arrays. The AC field is then switched off andparticles are trapped into microwells and thus mechanically confined.Excess beads are removed leaving behind a spatially ordered random beadarray on the substrate surface.

Substrates (e.g., chips) can be placed in one or more enclosedcompartments that permit samples and reagents to be transported in andout of the compartments through fluidic interconnection. Reactions canalso be performed in an open compartment format such as a microtiterplate. Reagents may be pipetted on top of the chip by robotic liquidhandling equipment, and multiple samples may be processedsimultaneously. Such a format accommodates standard sample processingand liquid handling for the existing microtiter plate format andintegrates sample processing and array detection.

In certain embodiments of this invention, encoded beads are assembled onthe substrate surface, but not in an array. For example, by spottingbead suspensions into multiple regions of the substrate and allowingbeads to settle under gravity, assemblies of beads can be formed on thesubstrate. In contrast to the bead arrays formed by LEAPS, theseassemblies generally assume disordered configurations of low-density ornon-planar configurations involving stacking or clumping of beads,thereby preventing imaging of affected beads. However, the combinationof spatial and color encoding attained by spotting mixtures ofchemically encoded beads into a multiplicity of discrete positions onthe substrate still allows multiplexing.

In certain embodiments, a comparison of an image of an array after theassay with a decoded image of the array can be used to reveal chemicallyor physically distinguishable characteristics, as well as the elongationof probes. This comparison can be achieved by using, for example, anoptical microscope with an imaging detector and computerized imagecapture and analysis equipment. The assay image of the array is taken todetect the optical signature that indicates the probe elongation. Thedecoded image is taken to determine the chemically and/or physicallydistinguishable characteristics that uniquely identify the probedisplayed on the bead surface. In this way, the identity of the probe oneach particle in the array may be identified by a distinguishablecharacteristic.

Image analysis algorithms may be used in analyzing the data obtainedfrom the decoding and the assay images. These algorithms may be used toobtain quantitative data for each bead within an array. The analysissoftware automatically locates bead centers using a bright-field imageof the array as a template, groups beads according to type, assignsquantitative intensities to individual beads, rejects “blemishes” suchas those produced by “matrix” materials of irregular shape in serumsamples, analyzes background intensity statistics and evaluates thebackground-corrected mean intensities for all bead types along with thecorresponding variances. Examples of such algorithms are set forth inPCT/US01/20179.

Probe elongation may be indicated by a change in the optical signature,or a change in chemical signature which may be converted to a change inoptical signature, originating from the beads displaying elongatedprobes, for example. Direct and indirect labeling methods well known inthe art are available for this purpose. Direct labeling refers to achange in optical signature resulting from the elongation; indirectlabeling refers to a change introduced by elongation which requires oneor more additional steps to produce a detectable optical signature. Incertain embodiments, fluorophore or chromophore dyes may be attached toone of the nucleotides added as an ingredient of probe elongation, suchthat probe elongation changes the optical signature of beads bychanging, for example, fluorescence intensities or by providing otherchanges in the optical signatures of beads displaying elongationproducts.

EXAMPLES

The present invention will be better understood from the Examples whichfollow. It should be understood that these examples are for illustrativepurposes and are not to be construed as limiting this invention in anymanner.

Example 1 Staggered Probe Design for Multiplexed SSP Analysis

Probes for each polymorphism are immobilized on a solid phase carrier toprovide a format in which multiple concurrent annealing and extensionreactions can proceed with minimal mutual interference. Specifically,this method provides a design which accommodates overlapping probes, asillustrated in FIG. 1. In this example, we consider three alleles:allele A, allele B and allele C. Probes 1 and 2 detect SNPs that arealigned with their respective 3′ termini while probes 3 and 4 detecttwo-nucleotide polymorphisms that are aligned with their respective 3′termini. The polymorphic sites targeted by probes 1 and 2 are locatedfive nucleotides upstream of those targeted by probes 3 and 4. Thisdesign permits each probe to bind its corresponding target and permitselongation to proceed when there is a perfect match at the designatedpolymorphic site. Thus, probes 1 and 3 match allele A, probe 2 andpossibly probe 3 match allele B, and probes 1 and 4 match allele C

Example 2 Probe Design for HLA Typing

To design probes for the analysis of the polymorphic region ranging frombase 106 to base 125 of the DRB gene, twenty-two different types ofsequences for the 20 base long fragment were located in the DRBdatabase. These are listed in the table below:

7 DRB1*0101 TTCTTGTGGCAGCTTAAGTT 104 DRB1*03011 TTCTTGGAGTACTCTACGTC 26DRB1*04011 TTCTTGGAGCAGGTTAAACA 1 DRB1*0434 TTCTTGGAGCAGGTTAAACC 3DRB1*07011 TTCCTGTGGCAGGGTAAGTA 1 DRB1*07012 TTCCTGTGGCAGGGTAAATA 28DRB1*0801 TTCTTGGAGTACTCTACGGG 1 DRB1*0814 TTCTTGGAGTACTCTAGGGG 1DRB1*0820 TTCTTGGAGTACTCTACGGC 1 DRB1*0821 TTCTTGGAGTACTCTATGGG 1DRB1*09012 TTCTTGAAGCAGGATAAGTT 2 DRB1*10011 TTCTTGGAGGAGGTTAAGTT 1DRB1*1122 TTCTTGGAGCAGGCTACACA 1 DRB1*1130 TTCTTGGAGTTCCTTAAGTC 18DRB1*15011 TTCCTGTGGCAGCCTAAGAG 9 DRB3*01011 TTCTTGGAGCTGCGTAAGTC 1DRB3*0102 TTCTTGGAGCTGTGTAAGTC 1 DRB3*0104 TTCTCGGAGCTGCGTAAGTC 16DRB3*0201 TTCTTGGAGCTGCTTAAGTC 1 DRB3*0212 TTCTTGCAGCTGCTTAAGTC 6DRB4*01011 TTCTTGGAGCAGGCTAAGTG 14 DRB5*01011 TTCTTGCAGCAGGATAAGTA

The first column contains the number of alleles sharing the sequencelisted in third column, the second column contains one of the allelenames. We selected the last three bases of the 20-base fragment as theTEI region and sorted the set of sequences according to their TEI regionto obtain the following groups:

1 104 DRB1*03011 TTCTTGGAGTACTCTACGTC e1 1 DRB1*1130TTCTTGGAGTgCctTAaGTC 9 DRB3*01011 TTCTTGGAGctgcgTAaGTC 1 DRB3*0102TTCTTGGAGctgTgTAaGTC 1 DRB3*0104 TTCTcGGAGctgcgTAaGTC 16 DRB3*0201TTCTTGGAGctgctTAaGTC e2 1 DRB3*0212 TTCTTGcAGctgctTAaGTC 2 7 DRB1*0101TTCTTGTGGCAGCTTAAGTT 1 DRB1*09012 TTCTTGaaGCAGgaTAAGTT 2 DRB1*10011TTCTTGgaGGAGgTTAAGTT 3 26 DRB1*04011 TTCTTGGAGCAGGTTAAACA 1 DRB1*1122TTCTTGGAGCAGGcTAcACA 4 1 DRB1*0434 TTCTTGGAGCAGGTTAAACC 5 3 DRB1*07011TTCCTGTGGCAGGGTAAGTA 14 DRB5*01011 TTCtTGcaGCAGGaTAAGTA 6 1 DRB1*07012TTCCTGTGGCAGGGTAAATA 7 28 DRB1*0801 TTCTTGGAGTACTCTACGGG e3 1 DRB1*0814TTCTTGGAGTACTCTAgGGG 1 DRB1*0821 TTCTTGGAGTACTCTAtGGG 8 1 DRB1*0820TTCTTGGAGTACTCTACGGC 9 18 DRB1*15011 TTCCTGTGGCAGCCTAAGAG 10 6DRB4*01011 TTCTTGGAGCAGGCTAAGTG

For sequences in the same group, variations between the first sequenceof the group and the rest are indicated in lower case. Three probesequences are used to illustrate the application of our probe designrules. The first sequence in the first group is selected as probe e1;the 6th sequence in the first group is selected as probe e2; and thefirst group in the 7th sequence is selected as probe e3.

Due to requirement for perfect complementarity of the target and theprobe's TEI region, sequences in group 2 to group 10 do not produceelongation products for e1 and e2. Similarly, sequences in groups otherthan the 7th group do not produce elongation products for e3. Each groupis distinctive from the others with respect to elongation reactionpatterns.

For sequences in the same group, there are two types of situations. Forexample, e1 and e2 differ by one nucleotide in 6 positions within theannealing region. Thus, targets matching e1 and e2 will not produceelongation products for the other sequences, and e1 and e2 are alsodistinct probes. Similarly, targets for the second to the 7th sequencesin group 1 will not produce elongation products for probe e1.

Except for the target matching e1, the remaining 5 sequences only differfrom e2 by one or two nucleotides as indicated below:

1, 2 ..............................M 16 DRB3* TTCTTGGAGCTGCTTAAGTC e20201  1 DRB1* TTCTTGGAGtTcCTTAAGTC a 1130  9 DRB3* TTCTTGGAGCTGCgTAAGTCb 01011  1 DRB3* TTCTTGGAGCTGtgTAAGTC c 0102  1 DRB3*TTCTcGGAGCTGCgTAAGTC d 0104  1 DRB3* TTCTTGcAGCTGCTTAAGTC e 0212

These sequences are cross-reactive. When targets for sequences b and e,which differ from e2 by one base at respective positions M-7 and M-14anneal to probe e2, the non-designated polymorphism(s) in the annealingregion will be tolerated and the elongation reaction will proceed tosubstantially the same degree as for perfectly matched sequences. Whentargets for sequences a, c, and d, which differ from e2 by twonucleotides anneal to probe e2, the elongation reaction will exhibitonly partial tolerance of the non-designated polymorphism(s). Oneapproach to improve on this situation is to provide separate probes fora, c, and d, then quantitatively analyze the yield of elongationproducts by analyzing signals intensities to identify the correctsequences. An alternative would be to bridge the non-designatedpolymorphisms in the annealing region altogether by adding a physicallinker (e.g., a tether) to the e2 probe to be able to separate annealingand TEI regions

For the sequences in the 7th group, the other two sequences will bepartially tolerated by the e3 probe. These three sequences may bepooled. The e2 probe will yield elongation products for 30 allelesinstead of 28 alleles.

Example 3 Utilizing Mismatch Tolerance To Modify Allele Binding Patterns

Probe DR-13e, GGACATCCTGGAAGACGA, was used to target the bases 281-299of the DRB gene. Thirty-four alleles, including allele DRB1*0103, areperfectly matched to this sequence. Thus, in the binding pattern, 13e ispositive for theses 34 alleles (that is, 13e will yield elongationproducts with these 34 alleles). Several additional alleles display thesame TEI region but display non-designated polymorphisms in theirrespective annealing regions. For example, five alleles, such asDRB1*0415, contain T in instead of A in position 4 while four alleles,such as DRB 1*1136, contain C in the that position. Due to mismatchtolerance in the annealing region, target sequences complementary tothese nine alleles will produce elongation reaction patterns similar tothat of the perfectly matched sequence. The result is shown in FIGS. 2.TO-3 and TO-4 are completely complementary sequences to allele *0415 and*1136, respectively.

DRB1*0103 GACATCCTGGAAGACGA 34 alleles DRB1*0415 GACTTCCTGGAAGACGA 5 alleles DRB1*1136 GACCTCCTGGAAGACGA  4 alleles

Example 4 Design of Linker Structure in the Probes to BridgeNon-Designated Polymorphisms

As illustrated in FIG. 3, an anchor sequence is derived from conservedsequence regions to ensure specific and strong annealing. It is notdesigned for polymorphism detection. For that purpose, a shortersequence for polymorphism detection is attached to the anchoringsequence by way of a neutral chemical linker. The shorter length of thesequence designed for polymorphism detection will limit potentialinterference to non-designated polymorphisms in the immediate vicinityof the designated site and thus decreases the number of possiblesequence combinations required to accommodate such interferingpolymorphisms This approach avoids highly dense polymorphic sites incertain situations. For example, it would be possible to distinguishbetween the sequences listed in Example 3 using a probe which takes intoaccount the additional polymorphism(s). Illustrative designs of thelinker and the sequences are listed below:

linker 13-5 AGCCAGAAGGAC/Spacer 18/spacer 18/GGAAGACGA linker 13-8AGCCAGAAGGAC/Spacer 18/spacer 18/AGACGA linker 13-11AGCCAGAAGGAC/Spacer 18/spacer 18/CGA

Example 5 Phasing

The present invention also is useful in reducing ambiguities that arisewhen two or more allele combinations can produce the same reactionpattern. In a simulated situation shown in FIGS. 4 and 5, allele Awhichmatches—and hence produces an elongation product with—Probe 1 and Probe3, and allele B, which matches Probe 2 and Probe 4 when present in thesame multiplexed reaction, generate the same total reaction pattern asdoes the combination of allele C which matches Probe 1 and 2, and alleleD which matches Probe 3 and Probe 4. Such ambiguity can be reduced oreliminated by using the detection methods provided in this invention toanalyze the elongation product of Probe 1 by hybridization using alabeled detection probe that is designed to target the same polymorphicsite as Probe 3. If the result of the analysis is positive, only oneallele combination, namely combination 1, is possible because Probe 1and Probe 3 are associated with the same allele. The detection probe canbe labeled by using any of the methods disclosed in this invention ormethods known in the art. If this identification detection step isperformed together with the multiplexed elongation reaction detection,different labels are used for the elongation detection and probehybridization detection as shown in the FIG. 5.

In this method, the ambiguity is resolved by assigning two or morepolymorphisms to the same “phase” using elongation in conjunction withhybridization. Phasing is rapidly emerging as an important concern forhaplotype analysis in other genetic studies designed in the art. Moreprobes can be included by reacting them with the target sequentially, orthey can be arranged in the same reaction with different labels fordetection.

The capability of combining probe elongation and hybridization reactionsis demonstrated in experiments using a sample sequence from HLA-B exon3. The result is shown in FIG. 6. A probe SB3P was elongated in thereaction and the elongated product was detected using a labeled DNAprobe. For the two samples presented in FIGS. 6A and 6B, SB 127r andSB3P, and SB285r and SB3P are in the same phase, respectively.

Example 6 Model HLA Typing Reaction Using Random Encoded Probe Arrays

To illustrate the discrimination of polymorphisms, a model reaction wasperformed using a synthetic single strand as the target. Color encoded,tosyl-functionalized beads of 3.2 μm diameter were used as solid phasecarriers. A set of 32 distinguishable color codes was generated bystaining particles using standard methods known in the art (Bangs. L.B., “Uniform Latex Particles”, Seragen Diagnostics Inc., p. 40) andusing different combinations of blue dye (absorption/emission 419/466nm) and green dye (absorption/emission 504/511). Stained beads werefunctionalized with Neutravidin (Pierce, Rockford, Ill.), a biotinbinding protein, to mediate immobilization of biotinylated probes. In atypical small-scale coupling reaction, 200 μl of suspension containing1% beads were washed three times with 500 μl of 100 mM phosphatebuffer/pH 7.4 (buffer A) and resuspended in 500 μl of that buffer. Afterapplying 20 μl of 5 mg/ml neutravidin to the bead suspension, thereaction was sealed and allowed to proceed overnight at 37° C. Coupledbeads were then washed once with 500 μl of PBS/pH 7.4 with 10 mg/ml BSA(buffer B), resuspended in 500 μl of that buffer and reacted for 1 hourat 37° C. to block unreacted sites on bead surface. After blocking,beads were washed three times with buffer B and stored in 200 μl of thatbuffer.

In the model reaction system, two pairs of probes were synthesized tocontain SNPs at their respective 3′ termini. The respective sequenceswere as follows:

SSP13: AAGGACATCCTGGAAGACG; SSP24: AAGGACATCCTGGAAGACA;SSP16: ATAACCAGGAGGAGTTCC SSP36: ATAACCAGGAGGAGTTCG.

The probes were biotinylated at the 5′ end; a 15-carbon triethyleneglycol linker was inserted between biotin and the oligonucleotide tominimize disruptive effects of the surface immobilization on thesubsequent reactions. For each probe, coupling to encoded beads wasperformed using 50 μl of bead suspension. Beads were washed once with500 μl of 20 mM Tris/pH 7.4, 0.5M NaCl (buffer C) and resuspended in 300μl of that buffer. 2.5 μl of a 100 μM solution of probe were added tothe bead suspension and allowed to react for 30 min at room temperature.Beads were then washed three times with 20 mM Tris/pH7.4, 150 mM NaCl,0.01% triton and stored in 20 mM Tris/pH 7.4, 150 mM NaCl.

The following synthetic targets of 33 bases in length were provided:

TA16: GTCGAAGCGCAGGAACTCCTCCTGGTTATGGAATA36: GTCGAAGCGCACGAACTCCTCCTGGTTATAGAATA13: GGCCCGCTCGTCTTCCAGGATGTCCTTCTGGCTTA24: GGCCCGCTTGTCTTCCAGGATGTCCTTCTGGCT

Targets were allowed to react with four probes (SSP13, SSP24, SSP16,SSP36) on the chip. An aliquot of 10 μl of a 100 nM solution of thetarget in annealing buffer of 0.2 M NaCl, 0.1% Triton X-100, 10 mMTris/pH 8.0, 0.1 mM EDTA was applied to the chip and allowed to reactfor 15 min at 30° C. The chip was then washed once with the same bufferand was then covered with an extension reaction mixture including: 100nM of TAMRA-ddCTP (absorption/emission: 550/580) (PerkinElmerBioscience, Boston, Mass.), 10 μM dATP-dGTP-dTTP, ThermoSequenase(Amersham, Piscataway, N. J.) in the associated buffer supplied by themanufacturer. The reaction was allowed to proceed for 5 min at 60° C.,and the chip was then washed in H₂O. Decoding and assay images of thechip were acquired using a Nikon fluorescence E800 microscope with anautomated filter changer containing hydroxy coumarin, HQ narrow band GFPand HQ Cy3 filters for blue, green decoding images and for the assayimage, respectively. An Apogee CCD KX85 (Apogee Instruments, Auburn,Calif.) was used for image acquisition. In each reaction, only theperfectly matching target was extended producing, in the case of theSNPs tested here, discrimination between matching and non-matchingtargets in the range from 13-fold to 30-fold; this is illustrated inFIG. 7 for TA13.

Example 7 HLA-DR Typing of Patient Sample

A DNA sample extracted from a patient was processed using a standard PCRprotocol. The following primers were used for general DR amplification:

forward primer: GATCCTTCGTGTCCCCACAGCACGreverse primer: GCCGCTGCACTGTGAAGCTCTC.

The PCR protocol was as follows: one cycle of 95° C. for 7 min, 35cycles of 95° C. for 30 sec, 60° C. for 30 sec and 72° C. for 1 min andone cycle of 72° C. for 7 min.

The PCR product, 287 bases in length and covering the DR locus, wasdenatured at 100° C. for 5 min, chilled on ice and mixed with annealingbuffer as described in Example 6 for the model reaction. An aliquot of10 ul was applied to each chip and reacted at 40° C. for 15 min. Theelongation reaction and subsequent image acquisition proceeded as in theprevious Example 6.

The multiplexed extension of sequence-specific probes using the PCRproduct produced from the patient sample produced results in accordancewith the probe design. Of the four probes tested in parallel (SSP13,SSP16, SSP24, SSP36), SSP13 was elongated while the SNP probe SSP24 onlyshowed background binding as did the unrelated SSP16 and SSP36 probes.As illustrated in FIG. 8, the multiplexed elongation of SSPsignificantly enhanced the discrimination between matching andnon-matching SNPs from approximately two-fold for an analysis based onthe hybridization of matching and non-matching sequence-specificoligonucleotide probes to at least 20-fold.

Example 8 Group-Specific Amplification

Primers for group-specific amplification (GSA) are most frequently usedwhen multiplexed hybridization with SSOs yields ambiguous assignments ofheterozygous allele combinations. In such a situation, GSA primers areselected to amplify selected sets of specific alleles so as to removeambiguities, a labor-intensive additional assay step which delays theanalysis. Using the methods of the present invention, preferably anembodiment of displaying probes on random encoded bead arrays, GSAprimers may be incorporated as probes into the multiplexed reactionthereby eliminating an entire second step of analysis.

Example 9 Analysis of HLA- DR, -A and -B Loci Using Cell Lines

Probes for the elongation-mediated multiplexed analysis of HLA-DR, HLA-Aand HLA-B were designed and tested using standard cell lines. The probeswere derived from SSP probes previously reported in the literature(Bunce, M. et al, Tissue Antigens. 46:355-367 (1995), Krausa, P andBrowning, M. J., Tissue Antigens. 47: 237-244 (1996), Bunce, M. et al,Tissue Antigens. 45:81-90 (1995)).

The probes used for DR were:

SR2: ACGGAGCGGGTGCGGTTG SR3: GCTGTCGAAGCGCACGG SR11: CGCTGTCGAAGCGCACGTTSR19: GTTATGGAAGTATCTGTCCAGGT SR23: ACGTTTCTTGGAGCAGGTTAAAC SR32:CGTTTCCTGTGGCAGGGTAAGTATA SR33: TCGCTGTCGAAGCGCACGA SR36:CGTTTCTTGGAGTACTCTACGGG SR39: TCTGCAGTAGGTGTCCACCA SR45:CACGTTTCTTGGAGCTGCG SR46: GGAGTACCGGGCGGTGAG SR48:GTGTCTGCAGTAATTGTCCACCT SR52: CTGTTCCAGGACTCGGCGA SR57:CTCTCCACAACCCCGTAGTTGTA SR58: CGTTTCCTGTGGCAGCCTAAGA SR60:CACCGCGGCCCGCGC SR67: GCTGTCGAAGCGCAAGTC SR71: GCTGTCGAAGCGCACGTA NEGAAAAAAAAAAAAAAAAAA

Some of the probes have a SNP site at their respective 3′ termini, forexample: SR3 and SR33 (G and A, respectively); SR11, SR67 and SR71 (T,C,and A, respectively). In addition, probes SR3 and 33 are staggered atthe 3′-end with respect to probes the group of SR11, 67 and 71 by onebase.

SR3 GCTGTCGAAGCGCACGG SR33 TCGCTGTCGAAGCGCACGA SR11 CGCTGTCGAAGCGCACGTTSR67 GCTGTCGAAGCGCAAGTC SR71 GCTGTCGAAGCGCACGTA

Reaction conditions were as described in Example 7 except that theannealing temperature was 55° C. instead of 40° C., and the extensiontemperature was 70° C. instead of 60° C. Double-stranded DNA was used asin Example 7. Single-stranded DNA generated better results under currentconditions. Single-stranded DNA was generated by re-amplifying theinitial PCR product in the same PCR program with only one of the probes.Results for two cell lines, W51 and SP0010, are shown in FIG. 9 and FIG.10. NEG, a negative control, was coupled to a selected type of bead.Signal intensity for other probes minus NEG was considered to be realsignal for the probe and the values were plotted in the figures. The Yaxis unit was the signal unit from the camera used in the experiment.The distinction between the positive and negative probes was unambiguousfor each sample. In particular, and in contrast to the situationtypically encountered in SSO analysis, it was not necessary to makecomparisons to other samples to determine a reliable threshold for eachprobe.

The probes used for HLA-A were:

SAD CACTCCACGCACGTGCCA SAF GCGCAGGTCCTCGTTCAA SAQ CTCCAGGTAGGCTCTCAA SARCTCCAGGTAGGCTCTCTG SAX GCCCGTCCACGCACCG SAZ GGTATCTGCGGAGCCCG SAAPCATCCAGGTAGGCTCTCAA SA8 GCCGGAGTATTGGGACGA SA13 TGGATAGAGCAGGAGGGT SA16GACCAGGAGACACGGAATA

Results for A locus exon 3, shown in FIG. 11 and FIG. 12, also wereunambiguous. FIG. 12 also shows an example of the mismatch tolerance fora non-designated polymorphism. That is, while allele 0201, displaying Cinstead of A at position M-18, is not perfectly matched to probe SAAP,the elongation reaction nonetheless proceeded because the polymerasedetected a perfect match for the designated polymorphism at the probe's3′ end and tolerated the mismatch at position M-18.

The probes used for IILA-B were:

SB220 CCGCGCGCTCCAGCGTG SB246 CCACTCCATGAGGTATTTCC SB229CTCCAACTTGCGCTGGGA SB272 CGCCACGAGTCCGAGGAA SB285 GTCGTAGGCGTCCTGGTCSB221 TACCAGCGCGCTCCAGCT SB197 AGCAGGAGGGGCCGGAA SB127CGTCGCAGCCATACATCCA SB187 GCGCCGTGGATAGAGCAA SB188 GCCGCGAGTCCGAGGACSB195 GACCGGAACACACAGATCTT

Experiments using these probes for typing HLA-B exon 2 were performedusing reference cell lines. As with HLA-A, unambiguous results (notshown here) were obtained.

Example 10 CF Mutation Analysis—Probe and Array Design for ProbeElongation

This Example describes the design and application of a planar array ofprobes, displayed on color-encoded particles, these probes designed todisplay several—most frequently two selected base compositions at ornear their respective 3′ ends and designed to align with designatedregions of interest within the CFTR target gene.

The CFTR gene sequence from Genebank (www.ncbi.nlm.nih.gov) was used todesign sixteen-mer probes for the multiplexed analysis of the 25 CFTRmutations in the ACMG-CF mutation panel. Probe sequences were designedusing PROBE 3.0 (http://www.genome.wi.mit.edu) and aligned withrespective exon sequences(http://searchlauncher.bcm.tmc.edu/seq-search/alignment.html).Oligonucleotides were designed to comprise 15 to 21 nucleotides, with a30-50% G+C rich.base composition and synthesized to contain a 5′ biotinTEG (Synthegen TX); to handle small deletions, the variable sequence ofthe TEI region was placed at or within 3-5 positions of the probe's 3′terminus. Probe compositions are listed in the table below.

A combination of 17 either pure blue or blue-green stained beads wereused with CF mutation analysis. The 48 base long Human β-actin gene(Accession #X00351) was synthesized and used in each reaction as aninternal positive control. Sixteen base long complementary probes wereincluded on each array. The CFTR gene sequence from Genebank(www.ncbi.nlm.nih.gov) was used for probe design for analysis of 25 CFTRmutations in the ACMG-CF mutation panel. The probe sequences weredesigned by PROBE 3.0 (http://www.genome.wi.mit.edu). Each probesequence was aligned with respective exon sequences(http://searchlauncher.bcm.tmc.edu/seq-search/alignment.html).Oligonucleotides were synthesized with a 5′ biotin TEG (Synthegen TX)and coupled on the surface of beads in presence of 0.5 M NaCl. Beadswere immobilized on the surface of a chip by LEAPS.

EXON MUTATIONS SEQUENCE  3 G85E CCC CTA AAT ATA AAA AGA TTC G85E-XCCC CTA AAT ATA AAA AGA TTT  4 1148 ATT CTC ATC TCC ATT CCA A 1148-XATT CTC ATC TCC ATT CCA G 621 + 1G > T TGT GTG CAA GGA AGT ATT AC 621 +1G > T-X TGT GTG CAA GGA AGT ATT AA R117H TAG ATA AAT CGC GAT AGA GCR117H-X TAG ATA AAT CGC GAT AGA GT  5 711 + 1G > TTAA ATC AAT AGG TAC ATA C TAA ATC AAT AGG TAC ATA A  7 R334WATG GTG GTG AAT ATT TTC CG R334W-X ATG GTG GTG AAT ATT TTC CA R347PATT GCC GAG TGA CCG CCA TGC R347P-X ATT GCC GAG TGA CCG CCA TGG 1078delTCAC AGA TAA AAA CAC CAC AAA 1078delT-X CAC AGA TAA AAA CAC CAC AA1078delT-X-2 CAC AGA TAA AAA CAC CAC A  9 A455ETCC AGT GGA TCC AGC AAC CG A455E-X TCC AGT GGA TCC AGC AAC CT 10 508CAT AGG AAA CAC CAA AGA T I507 CAT AGG AAA CAC CAA A F508CAT AGG AAA CAC CAA T 11 1717 − 1G > A CTG CAA ACT TGG AGA TGT CC 1717 −1G > A CTG CAA ACT TGG AGA TGT CT 551D TTC TTG CTC GTT GAC 551D-XTTC TTG CTC GTT GAT R553 TAAAGAAATTCTTGCTCG R553X TAAAGAAATTCTTGCTCAR560 ACCAATAATTAGTTATTCACC R560X ACCAATAATTAGTTATTCACG G542GTGTGATTCCACCTTCTC C G542X GTGTGATTCCACCTTCTC A INT-12 1898AGG TAT TCA AAG AAC ATA C 1898-X AGG TAT TCA AAG AAC ATA T 13 2183deLATGT CTG TTT AAA AGA TTG T 2183deLA-X TGT CTG TTT AAA AGA TTG C INT 14B2789 CAA TAG GAC ATG GAA TAC 2789-X CAA TAG GAC ATG GAA TAC T INT 163120 ACT TAT TTT TAC ATA C 3120-X ACT TAT TTT TAC ATA T 18 D1152ACT TAC CAA GCT ATC CAC ATC D1152 ACT TAC CAA GCT ATC CAC ATG INT 193849 + 10kbC > CCT TTC Agg GTG TCT TAC TCG T-WT1 3849 + 10kbC >CCT TTC Agg GTG TCT TAC TCA T-M1 19 R1162 AAT GAA CTT AAA GAC TCGR1162-X AAT GAA CTT AAA GAC TCA 3659delC-WT1 GTA TGG TTT GGT TGA CTT GG3659delCX-M1 GTA TGG TTT GGT TGA CTT GTA 3659delC-WT2GTA TGG TTT GGT TGA CTT GGT A 3659delCX-M2 GTA TGG TTT GGT TGA CTT GT A20 W1282 ACT,CCA AAG GCT TTC CTC W1282-X CT CCA AAG GCT TTC CTT 21N1303K TGT TCA TAG GGA TCC AAG N1303K-X TGT TCA TAG GGA TCC AAC b βActin AGG ACT CCA TGC CCA G

Probes were attached, in the presence of 0.5 M NaCl, to differentiallyencoded beads, stained either pure blue or blue-green Beads wereimmobilized on the surface of a chip using LEAPS. A synthetic 48 baseHuman β-actin gene (Accession #X00351) was included in each reaction asan internal positive control.

Array Design—In a preferred embodiment, the 25 CF mutations were dividedinto four different groups so as to minimize sequence homologies betweenmembers of each group. That is, mutations were sorted into separategroups so as to minimize overlap between probe sequences in any suchgroup and thereby to minimize cross-hybridization under conditions ofmultiplexed analysis. Each group, displayed on color-encoded beads, wasassembled into a separate array. (Results for this 4-chip array designare described in the following Example). Alternative robust arraydesigns also are disclosed herein.

Example 11 Multiplexed CF Mutation Analysis by Probe Elongation UsingREAD

Genomic DNA, extracted from several patients, was amplified withcorresponding probes in a multiplex PCR (mPCR) reaction using the methoddescribed in L. McCurdy, Thesis, Mount Sinai School of Medicine, 2000,which is incorporated by reference. This mPCR reaction uses chimericprimers tagged with a universal sequence at the 5′ end. Antisenseprimers were phosphorylated at the 5′ end (Synthegen, TX). Twenty eightamplificationcycles were performed using a Perkin Elmer 9600 thermalcycler, each cycle comprising a 10 second denaturation step at 94° C.with a 48 second ramp, a 10 second annealing step at 60° C. with a 36second ramp and a 40 second extension step at 72° C. with a 38 secondramp, each reaction (50 μl) containing 500 ng genomic DNA, 1×PCR buffer(10 mM Tris HCL, 50 mM KCL, 0.1% Triton X-100), 1.5 mM MgCl₂, 200 μMeach of PCR grade dNTPs and 5 units Taq DNA polymerase. Optimal probeconcentrations were determined for each probe pair. Followingamplification, products were purified to remove all reagents using acommercially available kit (Qiagen). DNA concentration was determined byspectrophotometric analysis.

PCR products were amplified with antisense 5′-phosphorylated primers. Toproduce single-stranded DNA templates, PCR reaction products wereincubated with 2.5 units of exonuclease in 1× buffer at 37° C. for 20min, followed by enzyme inactivation by heating to 75° C. for 10 min.Under these conditions, the enzyme digests one strand of duplex DNA fromthe 5′-phosphorylated end and releases 5′-phosphomononucleotides (J. W.Little, et al., 1967). Single-stranded targets also can be produced byother methods known in the art.

Single or pooled PCR products (20 ng each) were added to an annealingmixture containing 10 mM Tris-HCl, (pH 7.4) 1 mM EDTA, 0.2 M NaCl, 0.1%Triton X-100. The annealing mixture was placed in contact with theencoded array of bead-displayed CF probes (of Example 10) and incubatedat 37-55° C. for 20 minutes. The extension mixture—containing 3 U ofThermo Sequenase (Amersham Pharmacia Biotech NJ), 1× enzyme buffer witheither Fluorescein-labeled or TAMRA-labeled deoxynucleotide (dNTP)analogs (NEN Life Sciences) and 1 μmole of each type of unlabeleddNTP—was then added, and the elongation reaction was allowed to proceedfor 3 minutes at 60° C. The bead array was washed with deionized,sterilized water (dsH₂O) for 5-15 minutes. An image containing thefluorescence signal from each bead within the array was recorded using afluorescence microscope equipped with a CCD camera. Images were analyzedto determine the identity of each of the elongated probes. The resultsare shown in FIG. 15.

Example 12 Use of Covering Probes

Several SNPs have been identified within exon 10 of the CFTR gene. Thepolymorphisms in exon 10 are listed at the end of this Example. Thefollowing nine SNPs have been identified in the sequence of Δ508, themost common mutation in the CFTR gene (http://snp.cshl.org):

dbSNP213450 A/G

dbSNP180001 C/T

dbSNP1800093 G/T

1648 A/G

dbSNP100092 C/G

dbSNP1801178 A/G

dbSNP1800094 A/G

dbSNP1800095 G/A

Probes are designed to accommodate all possible SNPs are synthesized andcoupled to color-encoded beads. The primers for target amplification(described in Example 11) are also modified to take into account allpossible SNPs. The PCR-amplified target mediates the elongation ofterminally matched probes. The information collected from the analysisis twofold: identification of mutations and SNPs.

EXON 10 POLYMORPHISMS   1cactgtagct gtactacctt ccatctcctc aacctattcc aactatctga atcatgtgcc  61cttctctgtg aacctctatc ataatacttg tcacactgta ttgtaattgt ctcttttact 121ttcccttgta tcttttgtgc atagcagagt acctgaaaca ggaagtattt taaatatttt 181gaatcaaatg agttaataga atctttacaa ataagaatat acacttctgc ttaggatgat 241aattggaggc aagtgaatcc tgagcgtgat ttgataatga cctaataatg atgggtttta 301tttccagact tcaCttctaa tgAtgattat gggagaactg gagccttcag agggtaaaat 361taagcacagt ggaagaattt cattctgttc tcagttttcc tggattatgc ctggcaccat 421taaagaaaat AtCAtctTtg gtgtttccta tgatgaatat agatacagaa gcgtcatcaa 481agcatgccaa ctagaAgagG taagaaacta tgtgaaaact ttttgattat gcatatgaac 541ccttcacact acccaaatta tatatttggc tccatattca atcggttagt ctacatatat 601ttatgtttcc tctatgggta agctactgtg aatggatcaa ttaataaaac acatgaccta 661tgctttaaga agcttgcaaa cacatgaaat aaatgcaatt tattttttaa ataatgggtt 721catttgatca caataaatgc attttatgaa atggtgagaa ttttgttcac tcattagtga 781gacaaacgtc tcaatggtta tttatatggc atgcatatag tgatatgtgg t

Example 13 CF Mutation Analysis—On-Bead Probe Elongation with ModelSystem

FIG. 13 provides an overview of detection of CF gene mutation R117H. Thetarget was amplified by PCR as described in Example 11. Two 17-baseprobes variable at their 3′ ends were immobilized on color coded beads.The target nucleic acid sequence was added along with TAMRA-labeleddCTP, unlabeled dNTPs and thermostable DNA polymerase.

Complementary 17-mer oligonucleotide probes variable at the 3′ end weresynthesized by a commercial vendor (Synthegen TX) to contain 5′ biotinattached by way of a 12-C spacer (Biotin-TEG) and were purified byreverse phase HPLC. Probes were immobilized on color encoded beads.Probes were attached to color-encoded beads. A synthetic 48-meroligonucleotide also was provided to contain either A,T,C or G at adesignated variable site, corresponding to a cystic fibrosis genemutation at exon 4 (R117H).

1 μM of synthetic target was added to an annealing mixture containing 10mM Tris-HCL (pH 7.4) 1 mM EDTA, 0.2 M NaCl, 0.1% Triton X-100. Theannealing mixture was placed in contact with the encoded bead array andincubated at 37° C. for 20 minutes. An elongation mixture containing 3 Uof Thermo Sequenase (Amersham Pharmacia Biotech NJ), 1× enzyme bufferwith TAMRA-labeled deoxynucleotide (dNTP) analogs (NEN Life Sciences)and 1 μM of each type of unlabeled dNTP was then added, and theelongation reaction was allowed to proceed for 3 minutes at 60° C. Thebead array was then washed with dsH₂O for 5-15 minutes and an imagecontaining the fluorescence signal from each bead within the array wasrecorded using a fluorescence microscope equipped with a CCD camera.Images were analyzed to determine the identity of each of the elongatedprobes. The signal was analyzed by capturing the image by a CCD cameraand comparing signal intensity between two probes that can be decoded bythe bead color. The wild-type probe exactly matched the added target andtherefore yielded an elongation product, whereas no elongation wasobserved for the mutant probe. The results are shown in FIG. 16 a.

Example 14 CF Mutation Analysis—PCR with Bead-Tagged Primers andIntegrated Detection

This example illustrates probe elongation on the surface of beads insuspension, followed by assembly of and immobilization of beads on thesurface of a chip for image analysis. Oligonucleotides corresponding toCFTR gene mutation R117H were designed with variable 3′ ends (FIG. 14)and were synthesized to contain a 5′ biotin-TEG with a 12 C spacer(Synthegen, Texas). The probes were attached to blue stained beads asfollows: 2 μM of probe were added to a bead solution in 1×TE (100 mMTris-HCl, 10 mM EDTA), 500 mM NaCl and reacted for 45 min at roomtemperature. Beads were washed with 1×TE, 150 mM of NaCl for 3×, andsuspended in 50 μl of the same solution. One μl of each type of bead wasadded to PCR mix containing 1× buffer (100 mM Tris-HCl, pH. 9.0, 1.5 mMMgCl₂ 500 mM KCl), 40 μM Cy5-labeled dCTP (Amersham Pharmacia BiotechNJ), and 80 μM of the other three types of dNTPs, and 3 U of Taq DNApolymerase (Amersham Pharmacia Biotech NJ). Wild type complementarytarget (40 ng) was added to the PCR mix just before amplification.Eleven cycles of PCR amplification were performed in a Perkin Elmer 9600thermal cycler, each cycle consisting of denaturation for 30 s at 90°C., annealing for 30 s at 55° C., and elongation at 72° C. for 20 sAfter amplification, beads were washed four times by centrifugation in1×TE buffer. and placed on the chip surface. Images were recorded as inprevious Examples and analyzed using the software described in WO01/98765. The results show specific amplification for beads coupled withthe wild-type probe, but no amplification for beads coupled with themutant probe. The results are shown in FIG. 16 b.

This example demonstrates the integration of multiplexed PCR usingbead-tagged probes with subsequent assembly of beads on planar surfacesfor instant imaging analysis. In a preferred embodiment, amicrofluidically connected multicompartment device may be used fortemplate amplification as described here. For example, a plurality ofcompartments capable of permitting temperature cycling and housing, ineach compartment, one mPCR reaction producing a subset of all desiredamplicons may be used as follows: (1) perform PCR with different probepairs in each of four compartments, using encoded bead-tagged primers asdescribed in this Example; (2) following completion of all PCRreactions, pool the amplicon-displaying beads; (3) assemble randomarray; and (4) record image and analyze the data. Array assembly may beaccomplished by one of several methods of the prior art including LEAPS.

Example 15 CF Mutation Analysis—One-Step Annealing and Elongation inTemperature-Controlled Reactor

Genomic DNA, extracted from several patients, was amplified withcorresponding primers in a multiplexed PCR (mPCR) reaction, as describedin Example 11. Following amplification, products were purified to removeall reagents using a commercially available kit (Qiagen). DNAconcentration was determined by spectrophotometric analysis. Single orpooled PCR products (20 ng each) were added to an annealing mixturecontaining 10 mM Tris-HCL (pH 7.4) 1 mM EDTA, 0.2 M NaCl, 0.1% TritonX-100. The annealing mixture was mixed with elongation mixturecontaining 3 U of Thermo Sequenase (Amersham Pharmacia Biotech, NJ), 1×enzyme buffer with either fluorescein-labeled or TAMRA-labeleddeoxynucleotide (dNTP) analogs (NEN Life Sciences) and 1-10 μmole ofeach type of unlabeled dNTP and placed in contact with an array ofoligonucleotide probes displayed on a color-encoded array.Oligonucleotides were designed and synthesized as in previous Examples.The annealing- and elongation reactions were allowed to proceed in atemperature controlled cycler. The temperature steps were as follows:three minutes each at 65° C., 60° C., 55° C., 50° C. and 45° C., with aramp between temperatures of less than 30 seconds. The bead array wasthen washed with dsH₂O for 5 to 15 min. and an image containing thefluorescence signal from each bead within the array was recorded using afluorescence microscope equipped with a CCD camera. Images were analyzedto determine the identity of each of the elongated probes. Typicalresults are shown in FIG. 17.

Example 16 Pooling of Covering Probes

To analyze designated polymorphisms, 20-mer oligonucleotide elongationprobes of 30-50% G+C base composition were designed to contain avariable site (G/T) at the 3′ end, to be aligned with the designatedpolymorphic site. Two non-designated polymorphic sites were anticipatedat position 10 (C/A) and at 15 (T/G). A summary of the design follows:

Wild-Type Probe Sequence:

-   -   Oligo 1: “G” at position 20, “C” at 10, and “T” at 15.    -   Oligo 2: “G” at position 20, “C” at 10, and “G” at 15.    -   Oligo 3: “G” at position 20, “A” at 10, and “T” at 15.    -   Oligo 4: “G” at position 20, “A” at 10, and “G” at 15.

Mutant Probe Sequence:

-   -   Oligo 1: “T” at position 20, “C” at 10, and “T” at 15.    -   Oligo 2: “T” at position 20, “C” at 10, and “G” at 15.    -   Oligo 3: “T” at position 20, “A” at 10, and “T” at 15.    -   Oligo 4: “T” at position 20, “A” at 10, and “G” at 15.

All of the probes were pooled and attached to a single type ofcolor-coded bead using protocols of previous Examples. Whensingle-stranded target is added to these beads displaying pooled probes,one of the probes will yield elongation product as long as it isperfectly aligned with the designated polymorphism.

Example 17 Designated Polymorphisms in Heterozygous and HomozygousConfigurations

To distinguish between heterozygous and homozygous configurations, thedesign of the previous Example is augmented to contain a second set ofprobes to permit the identification of the C/A designated polymorphismaligned with the probes' 3′ ends, and to permit calling of heterozygousversus homozygous mutations.

As in the previous example, two non-designated polymorphic sites areanticipated at positions 10 (C/A) and 15 (T/G). A summary of the designfollows:

-   -   Set #1:        -   Oligo 1: “C” at position 20, “C” at 10, and “T” at 15.        -   Oligo 2: “C” at position 20, “C” at 10, and “G” at 15.        -   Oligo 3: “C” at position 20, “A” at 10, and “T” at 15.        -   Oligo 4: “C” at position 20, “A” at 10, and “G” at 15.    -   Set #2:        -   Oligo 5: “A” at position 20, “C” at 10, and “T” at 15.        -   Oligo 6: “A” at position 20, “C” at 10, and “G” at 15.        -   Oligo 7: “A” at position 20, “A” at 10, and “T” at 15.        -   Oligo 8: “A” at position 20, “A” at 10, and “G” at 15.

Oligonucleotides from set #1 are pooled and attached to a single type ofcolor (e.g. green) coded bead using protocols of previous Examples.Oligonucleotides from set #2 were pooled and attached to a second typeof color (e.g. orange) coded bead using protocols of previous Examples.Beads were pooled and immobilized on the surface of chip as describedearlier. Next, target was introduced, and on-chip reactions performed asdescribed in previous Examples. If probes on green beads only areelongated, the individual has a normal (or wild-type) allele. If probeson orange beads only are elongated, the individual is homozygous for themutation. I If probes on green as well as origan beads are elongated,the individual is heterozygous for that allele. This design is usefulfor the identification of known and unknown mutations.

Example 18 Confirmatory Sequencing (“Resequencing”)

The design of the present invention can be used for re-sequencing of aspecific arca. This test can be used when on-chip probe elongationreaction requires confirmation, as in the case of reflex tests forI506V, I507V, F508C and 7T in the CF mutation panel. The sequence inquestion, here 20 bases to 30 bases in length, is sequenced on-chip bymultiplexed interrogation of all variable sites. This is accomplished bydesigning specific probes for ambiguous locations, and by probe—poolingas described in Examples 16 and 17.

Example 19 Elongation with One Labeled dNTP and Three Unlabeled dNTPs

By way of incorporating at least one labeled dNTP, all elongationproducts are detected in real-time and identified by their associationwith coded solid phase carriers. Using assay conditions described inconnection with Examples 6 and 7, tetramethylrhodamine-6-dCTP andunlabeled dATP, dTTP and dGTP were provided in an elongation reaction toproduce a fluorescently labeled elongation product as illustrated FIG.18. Other dye labeling of dNTPs (as in BODIPY-labeled dUTP andCy5-labeled dUTP) may be used. Similarly, any other labeled dNTP can beused. The length of the elongation product depends on the amount oflabeled dNTP tolerated by the DNA polymerase. Available enzymesgenerally exhibit a higher tolerance for strand-modifying moieties suchas biotin and digoxigenin which may then be reacted in a second stepwith labeled avidins or antibodies to accomplish indirect labeling ofelongation products. When using these small molecules, elongationproducts measuring several hundred bases in length are produced.

Example 20 Extension with One Labeled ddNTP, Three Unlabeled dNTPs

TAMRA-labeled ddCTP may be incorporated to terminate the extensionreaction, as illustrated in FIG. 19. On-chip reactions usingTAMRA-labeled ddCTP were performed as described in Examples 6 and 7. Ina reaction mixture containing TAMRA-ddCTP and unlabeled dTTP, dATP anddGTP, following annealing of the target to the matching probe, theextension reaction terminates when it completes the incorporation of thefirst ddCTP. This may occur with the very first base incorporated,producing a single base extension product, or it may occur after anumber of unlabeled dNTPs have been incorporated.

Example 21 Elongation with Four Unlabeled dNTPs, Detection byHybridization of Labeled Probe

Probes are elongated using a full set of four types of unlabeled dNTPs,producing, under these “native” conditions for the polymerase,elongation products measuring several hundred bases in length, limitedonly by the length of the annealed template and on-chip reactionconditions. The elongation product is detected, following denaturationat high temperature, in a second step by hybridization with a labeledoligonucleotide probe whose sequence is designed to be complementary toa portion of the elongation product This process is illustrated in FIG.20.

Example 22 Elongation with Four Unlabeled dNTPs, Detection via LabeledTemplate

As with standard protocols in routine use in multiplexed hybridizationassays, the DNA target to be analyzed can itself be labeled in thecourse of PCR by incorporation of labeled probes. Under conditions suchas those described in Examples 6 and 7, a labeled target is annealed toprobes. Matching probes are elongated using unlabeled dNTPs. Followingcompletion of the elongation reaction, detection is performed by settingthe temperature (T_(det)) to a value above the melting temperature(T_(non-match)) of the complex formed by target and non-matched probe,but below the melting temperature (T_(match)) of the complex formed bytarget and matched, and hence elongated, 1 probe. The latter complex,displaying a long stretch of duplex region, will be significantly morestable than the former so that (T_(non-match))<T<(T_(match)). Typicalvalues for T are in the range of 70° C. to 80° C. Under theseconditions, only the complex formed by target and elongated probe willstable, while the complex formed by target and non-matching probe, andhence the fluorescence signal from the corresponding solid phasecarrier, will be lost. That is, in contrast to other designs, it is thedecrease of signal intensity associated with the non-matching probewhich is detected, rather than the increase in intensity associated thematching probe. FIG. 21 illustrates the design which eliminates the needfor labeled dNTPs or ddNTPs. This is useful in the preferred embodimentsof this invention, where labeled dNTPs or ddNTPs can absorbnon-specifically to encoded particles, thereby increasing the backgroundof the signal and decreasing the discriminatory power of the assays. Inaddition, by using a labeled target, this protocol is directlycompatible with methods of polymorphism analysis by hybridization ofsequence-specific oligonucleotides.

Example 23 Real-Time on-Chip Signal Amplification

A standard temperature control apparatus used with a planar geometrysuch as that illustrated in FIG. 22 permits the application ofprogrammed temperature profiles to a multiplexed extension of SSPs.Under conditions of Examples 6 and 7, a given template mediates theelongation of one probe in each of multiple repeated“denature-anneal-extend” cycles. In the first cycle, a target moleculebinds to a probe and the probe is elongated or extended. In the nextcycle, the target molecule disassociates from the first probe in the“denature” phase (at a typical temperature of 95° C.), then anneals withanother probe molecule in the “anneal” phase (at a typical temperatureof 55° C.) and mediates the extension of the probe in the “extend” phase(at a typical temperature of 72° C.). In N cycles, each templatemediates the extension of N probes, a protocol corresponding to linearamplification (FIG. 30). In a preferred embodiment of this invention, inwhich planar arrays of encoded beads are used to display probes in amultiplexed extension reaction, a series of temperature cycles isapplied to the reaction mixture contained between two planar, parallelsubstrates. One substrate permits direct optical access and directimaging of an entire array of encoded beads. The preferred embodimentprovides for real-time amplification by permitting images of the entirebead array to be recorded instantly at the completion of each cycle.

Genomic, mitochondrial or other enriched DNA can be used for directdetection using on-chip linear amplification without sequence specificamplification. This is possible when an amount of DNA sufficient fordetection is provided in the sample. In the bead array format, if 10⁴fluorophores are required for detection of signal from each bead, 30cycles of linear amplification will reduce the requisite number to ˜300.Assuming the use of 100 beads of the requisite type within the array,the requisite total number of fluorophores would be ˜10⁵, a numbertypically available in clinical samples. For example, typical PCRreactions for clinical molecular typing of HLA are performed with 0.1 to1 μg of genomic DNA. One μg of human genomic DNA corresponds toapproximately 10⁻¹⁸ moles, thus, 6×10⁵ copies of the gene of interestThis small amount of sample required by the miniaturized bead arrayplatform and on-chip amplification makes the direct use of pre-PCRsamples possible. This not only simplifies sample preparation but, moreimportantly, eliminates the complexity of multiplexed PCR, frequently arate limiting step in the development of multiplexed genetic analysis.

Example 24 Construction of a Probe Library for Designated and UnselectedPolymorphisms for CF Mutation Analysis

To increase the specificity of elongation probes and avoid falsepositives, elongation probes were designed to accommodate all knownpolymorphisms present in a target sequence. In addition, PCR primerswere designed taking into consideration designated and non-designatedpolymorphisms.

The G/C mutation at position 1172. of R347P on Exon 7 within the CFTRgene, one of 25 mutations within the standard population carrierscreening panel for cystic fibrosis, was selected as a designatedpolymorphism. There are 3 CF mutations within Exon 7 included in themutation panel for general population carrier screening(http://www.faseb.org/genetics/acmg). A polymorphism G/T/A at the samesite has been reported (http://www.genet.sickkids.on.ca/cftr), and inaddition, non-designated polymorphisms have been reported at positions1175, 1178, 1186, 1187 and 1189. All of these polymorphisms caninterfere with desired probe elongation.

The construction of a set of degenerate probes for eMAP is illustratedbelow for R347P (indicated by the bold-faced G) which is surrounded bynumerous non-designated polymorphisms, indicated by capital letters:

Normal Target Sequence for Elongation: 5′                      3′Gca Tgg Cgg tca ctC GgC a Degenerate Elongation Probe Set:Ngt Ycc Ycc agt gaY RcY t 3′                      5′where N=a, c, g or t; R (puRines)=a or g and Y (pyrimidines)=c or t,implying a degeneracy of 128 for the set.

Primer Pooling for Mutation Analysis—The principal objective in theconstruction of a degenerate set is to provide at least one probesequence to match the target sequence sufficiently closely to ensureprobe annealing and elongation. While this is always attainable inprinciple by providing the entire set of possible probe sequencesassociated with the designated polymorphism, as in the preferred mode ofconstructing covering sets, the degree of degeneracy of that set, 128 inthe example, would lead to a corresponding reduction in assay signalintensity by two orders of magnitude if all probes were to be placedonto a single bead type for complete probe pooling. Splitting poolswould improve the situation by distributing the probe set over multiplebead types, but only at the expense of increasing array complexity.

First, the probe pool was split into a minimum of two or more pools,each pool providing the complementary composition, at probe position M(i.e., the probe's 3′ terminus), for each of the possible compositionsof the designated polymorphic site. In the example, four such pools arerequired for a positive identification of the designated targetcomposition. Next, non-designated polymorphic sites were examinedsuccessively in the order of distance from the designated site. Amongthese, positions within the TEI region are of special importance toensure elongation. That is, each pool is constructed to contain allpossible probe compositions for those non-designated sites that fallwithin the TEI region. Finally, as with the construction of degenerateprobes for cloning and sequencing of variable genes, the degeneracy ofthe set is minimized by placing neutral bases such as inosine into thoseprobe positions which are located outside the TEI region provided theseare known never to be juxtaposed to G in the target. In the example,non-designated polymorphisms in probe positions M-16 and M-18 qualify.That is, the minimal degeneracy of each of the four pools would increaseto four, producing a corresponding reduction in signal intensity. As anempirical guideline, signal reduction preferably will be limited to afactor of eight.

In total, four pools, each uniquely assigned to one bead type andcontaining eight degenerate probe sequences, will cover the targetsequence. These sequences are analogous to those shown below for poolsvariable at M:

Probe pool for CF mutation R347P R347P Cgt Acc Gcc agtgaG GgC 3′                     5′ POOL 1 Cgt Acc Gcc agt gaG IgICgt Acc Gcc agt gaC IgI Cgt Acc Ccc agt gaG IgI Cgt Acc Ccc agt gaC IgICgt Tcc Gcc agt gaG IgI Cgt Tcc Gcc agt gaC IgI Cgt Tcc Ccc agt gaG IgICgt Tcc Ccc agt gaC IgI POOL 2 Ggt Acc Gcc agt gaG IgIGgt Acc Gcc agt gaC IgI Ggt Acc Ccc agt gaG IgI Ggt Acc Ccc agt gaC IgIGgt Tcc Gcc agt gaG IgI Ggt Tcc Gcc agt gaC IgI Ggt Tcc Ccc agt gaG IgIGgt Tcc Ccc agt gaC IgI POOL 3 Agt Acc Gcc agt gaG IgIAgt Acc Gcc agt gaC IgI Agt Acc Ccc agt gaG IgI Agt Acc Ccc agt gaC IgIAgt Tcc Gcc agt gaG IgI Agt Tcc Gcc agt gaC IgI Agt Tcc Ccc agt gaG IgIAgt Tcc Ccc agt gaC IgI POOL 4 Tgt Acc Gcc agt gaG IgITgt Acc Gcc agt gaC IgI Tgt Acc Ccc agt gaG IgI Tgt Acc Ccc agt gaC IgITgt Tcc Gcc agt gaG IgI Tgt Tcc Gcc agt gaC IgI Tgt Tcc Ccc agt gaG IgITgt Tcc Ccc agt gaC IgI

In general, the type of non-designated polymorphisms on the antisensestrand may differ from that on the sense strand, and it may then beadvantageous to construct degenerate probe sets for the antisensestrand. As with the construction of degenerate elongation probes,degenerate hybridization probe sets may be constructed by analogousrules to minimize the degeneracy.

Example 25 “Single Tube” CF Mutation Analysis by eMAP

This example is concerned with methods and compositions for performingan eMAP assay, wherein the annealing and elongation steps occur in thereactor. This embodiment is useful because it obviates the need forsample transfer between reactors as well as purification or extractionprocedures, thus simplifying the assay and reducing the possibility oferror. A non-limiting exemplary protocol follows.

Genomic DNA extracted from several patients was amplified withcorresponding primers in a multiplex PCR (mPCR) reaction. The PCRconditions and reagent compositions were as follows.

PRIMER DESIGN: Sense primers were synthesized without any modificationand antisense primers with “Phosphate” at the 5′ end. Multiplex PCR wasperformed in two groups. Group one amplification includes exon 5, 7, 9,12, 13, 14B, 16, 18 and 19. Amplifications for group 2 includes primersfor exon 3, 4, 10, 11, 20, 21 and intron 19. The 5′ phosphate groupmodification on exon 5, 7, and 11 was included on forward primer to useantisense target for probe elongation. While sense target was used forall other amplicons by placing phosphate group on reverse primer.

PCR Master Mix Composition

For 10 ul reaction/sample:

Components Volume (μl) 10X PCR buffer 1.0 25 mM MgCl₂ 0.7 dNTPs (2.5 mM)2.0 Primer mix (Multiplex 10x) 1.5 Taq DNA polymerase 0.3 ddH2O 1.5 DNA3.0 Total 10

PCR Cycling

94° C. 5 min, 94° C. 10 sec., 60° C. 10 sec., 72° C. 40 sec

72° C. 5 min., Number of cycles: 28-35

The reaction volume can be adjusted according to experimental need.Amplifications are performed using a Perkin Elmer 9600 thermal cycler.Optimal primer concentrations were determined for each primer pair.Following amplifications, 5 ul of the product was removed for gelelectrophoresis. Single stranded DNA targets were generated as follows:Two microliters of exonuclease was added to 5 μl of PCR product,incubated at 37° C. for 15 minutes and enzyme was denatured at 80° C.for 15 minutes. After denaturation, 1 μl of 10× exonuclease buffer wasadded with 1 μl of λ exonuclease (5 U/μl) and incubated at 37° C. for 20minutes and the reaction was stopped by heating at 75° C. for 10minutes.

On Chip Elongation

Wild type and mutant probes for 26 CF mutations were coupled on the beadsurface and assembled on the chip array. The probes were also dividedinto two groups. A third group was assembled for reflex test including5T/7T/9T polymorphisms.

Elongation Group 1, total 31 groups on the chip surface.

Bead cluster # Mutation 1 G85E-WT 2 G85E-M 3 621 + 1G > T-WT 4 621 +1G > T-M 5 R117H-WT 6 R117H-M 7 β Actin 8 I148T-WT 9 I148T-M 10 508-WT11 F508 12 I507 13 G542X-WT 14 G542X-M 15 G551D-WT 16 G551D-M 17R553X-WT 18 R553X-M 19 BIOTIN 20 1717 − 1G > A-WT 21 1717 − 1G > A-M 22R560T-WT 23 R560T-M 24 3849 + 10kbT-WT 25 3849 + 10kbT-M 26 W1282X-WT 27W1282X-M 28 N1303K-WT 29 N1303K-M 30 OLIGO-CElongation Group 2, total 28 groups on the chip surface.

Cluster # Mutation 1 711 + 1G > T-WT 2 711 + 1G > T-M 3 R334W-WT 4R334W-M 5 1078delT-WT 6 1078delT-M 7 β Actin 8 R347P-WT 9 R347P-M 10A455E-WT 11 A455E-M 12 1898 + 1G > A-WT 13 1898 + 1G > A-WT 142184delA-WT 15 2184delA-M 16 2789 + 5G-WT 17 2789 + 5G-M 18 BIOTIN 193120 + 1G > A-WT 20 3120 + 1G > A-WT 21 R1162X-WT 22 R1162X-M 233659delC-WT 24 3659delC-M 25 D1152-WT 26 D1152-M 27 OLIGO-CmPCR group 2:Elongation Group 3, total 6 groups

Cluster # Mutation 1 β Actin 1 Oligo C 2 5T 3 7T 4 9T 5 Biotin

Elongation reaction buffer has been optimized for use in uniplcx and/ormultiplex target elongation assays and composed of, Tris-HCL (pH 8.5)1.2 mM, EDTA 1 uM, DTT 10 μM, KCl 1 μM, MgCl₂ 13 μM, 2-Mercaptoethanol10 μM, Glycerol 0.5%, Tween-20 0.05%, and Nonidet 0.05%. Ten microlitersof elongation reaction mixture was added on each chip containing 1×Reaction buffer 0.1 μM of Labeled dNTP, 1.0 μM of dNTPs mix, 3 U of DNApolymerase and 5 (˜5 ng) of target DNA (patient sample). The reactionmix was added on the chip surface and incubated at 53° C. for 15 min andthen at 60° C. for 3 min. The chip was washed with wash buffercontaining 0.01% SDS, covered with a clean cover slip and analyzed usinga Bioarray Solutions imaging system. Images are analyzed to determinethe identity of each of the elongated probes.

Example 26 CF Mutation Analysis—Single Tube Single Chip-One StepElongation

Probes for 26 CF mutations and controls were coupled on the surface of51 types of beads. Probe coupled beads were assembled on the surface ofa single chip. Genomic DNA was extracted from several patients and wasamplified with corresponding primers in a multiplexed PCR (mPCR)reaction, as described in the previous example. Following amplification,single stranded DNA products were produced using X exonuclease. Singleor pooled PCR products (˜5 ng) were added to a reaction mixturecontaining reaction buffer, deoxynucleotide (dNTP) analogs (NEN LifeSciences), each type of unlabeled dNTP, and DNA polymerase (AmershamPharmacia Biotech, NJ). The annealing/elongation reaction was allowed toproceed in a temperature controlled cycler. The temperature steps wereas follows: 20 minutes at 53° C., and 3 minutes at 60° C. The bead arraywas then washed with dsH₂O containing 0.01% SDS for 5 to 15 minutes. Animage containing the fluorescent signal form each bead within the arraywas recorded using a fluorescence microscope and a CCD camera. Imageswere analyzed to determine the identity of each of the elongated probes.

The composition of bead chip containing 26 CF mutations is providedbelow.

Elongation Group 4, total 51 groups

Cluster # Mutation 1 β Actin 2 G85E-WT 3 G85E-M 4 621 + 1G > T-WT 5621 + 1G > T-M 6 R117H-WT 7 R117H-M 8 I148T-WT 9 I148T-M 10 711 + 1G >T-WT 11 711 + 1G > T-M 12 A455E-WT 13 A455E-M 14 508-WT 15 F508 16 I50717 R533-WT 18 R533-M 19 G542-WT 20 G542-M 21 G551D-WT 22 G551D-M 23R560-WT 24 R560-M 25 1898 + 1G-WT 26 1898 + 1G-M 27 2184delA-WT 282184delA-M 29 2789 + 5G > A-WT 30 2789 + 5G > A-M 31 3120 + 1G-WT 323120 + 1G-WT 33 D1152-WT 34 D1152-M 35 R1162-WT 36 R1162-M 37 OLIGO-C 38W1282X-WT 39 W1282-M 40 N1303K-WT 41 N1303-M 42 R334-WT 43 R334-M 441078delT-WT 45 1078delT-M 46 3849-10kb-WT 47 3849-10kb-M 49 1717 − 1G >A-WT 50 1717 − 1G > A-WT 51 Biotin

Example 27 Identification of Three or More Base Deletions and/orInsertions by eMAP

Elongation was used to analyze mutations with more than 3 base deletionsor insertions. Probes were designed by placing mutant bases 3-5 basebefore 3′ end. The wild type probes were designed to either include orexclude mutant bases (terminating before mutations). The following is anexample of mutations caused by a deletion of ATCTC and/or insertion ofAGGTA. The probe designs are as follows:

1. WT1- ----------------------ATCTCgca 2. WT2- ----------------------3. M1- ----------------------gca (deletion only) 4. M2-----------------------AGGTAgca (deletion and insertion)

Wild type probes were either coupled on the surface of differentiallyencoded beads or pooled as described in this invention. Probes formutation 1 (M1: deletion) and 2 (M2: insertion) were coupled ondifferent beads. Both wild type probes provide similar information,while the mutant probes can show the type of mutation identified in aspecific sample.

Example 28 Hairpin Probes

In certain embodiments of this invention, bead-displayed priming probesform hairpin structures. A hairpin structure may include a sequencefragment at the 5′ end that is complementary to the TEI region and theDA sequence, as shown in FIG. 23. During a competitive hybridizationreaction, the hairpin structure opens whenever the DA regionpreferentially hybridizes with the target sequence. Under thiscondition, the TEI region will align with the designated polymorphicsite and the elongation reaction will occur. The competitive nature ofthe reaction can be used to control tolerance level of probes.

Example 29 Analysis of Cystic Fibrosis and Ashkenazi Jewish DiseaseMutations by Multiplexed Elongation of Allele Specific OligonucleotidesDisplayed on Custom Bead Arrays

A novel assay for the high throughput multiplexed analysis of mutationshas been evaluated for ACMG+ panel of Cystic Fibrosis mutations. Inaddition, an Ashkenazi Jewish disease panel also has been developed todetect common mutations known to cause Tay-Sachs, Canavan, Gaucher,Niemann-Pick, Bloom Syndrome, Fancomi Anemia, Familial Dysautonomia, andmucolipodosis IV.

In elongated-mediated multiplexed analysis of polymorphisms (eMAP),allele specific oligonucleotides (ASO) containing variable 3′ terminalsequences are attached to color-encoded beads which are in turn arrayedon silicon chips. Elongation products for normal and mutant sequencesare simultaneously detected by instant imaging of fluorescence signalsfrom the entire array.

In this example, several hundred clinical patient samples were used toevaluate ACMG CF bead chips. As shown in FIG. 24, the assay correctlyscored all of the mutations identified by standard DNA analysis.

In summary, a multiplexed elongation assay comprising customized beadswas used to study mutations corresponding to ACMG+ and Ashkenazi diseasepanels. The customized beads can be used for DNA and protein analysis.The use of these customized beads are advantageous for several reasonsincluding (1) instant imaging—the turnaround time for the assay iswithin two hours (2) automated image acquisition and analysis (3)miniaturization, which means low reagent consumption, and (4) thebeadchips are synthesized using wafer technology, so that millions ofchips can be mass-produced, if desired.

1. A method of concurrent determination of nucleotide composition atdesignated polymorphic sites located within one or more targetnucleotide sequences, said method comprising the following steps: a.Providing one or more sets of probes, each probe capable of annealing toa subsequence of said one or more target nucleotide sequences locatedwithin a range of proximity to a designated polymorphic site; b.Contacting the set of probes with said one or more target nucleotidesequences so as to permit formation of hybridization complexes byplacing an interrogation site within a probe sequence in directalignment with the designated polymorphic site; c. For eachhybridization complex, determining the presence of a match or a mismatchbetween the interrogation site and a designated polymorphic site; and d.Determining the composition of the designated polymorphic site. 2.-48.(canceled)
 49. A probe comprising: a. an oligonucleotide sequencecomprising a 5′ end and a 3′ end; b. a Terminal Elongation Initiation(TEI) region comprising the last 4 nucleotides at the 3′ end of thesequence; and c. a Duplex Anchoring (DA) region which forms an annealingcomplex with a target nucleotide sequence; wherein the sequencecomprises one or more nucleotides corresponding to polymorphisms in thetarget.
 50. The probe of claim 49, wherein said TEI region comprises atleast one or more mismatches to the target nucleotide sequence.
 51. Theprobe of claim 49, wherein said DA region exactly matches thecorresponding target nucleotide sequence.
 52. The probe of claim 49,wherein the DA region is 5′ to the nucleotides corresponding topolymorphisms to the target nucleotide sequence.
 53. The probe of claim52, wherein the DA region is 3-5 nucleotides from at least one mismatchto the target sequence.
 54. The probe of claim 49, wherein the TEIregion comprises one or more mismatches to the target nucleotidesequence.
 55. The probe of claim 49, wherein an elongation reaction canbe initiated from the TEI region.
 56. The probe of claim 49, wherein theDA region is longer than the TEI region.
 57. The probe of claim 49,wherein said probe is immobilized on an encoded substrate.
 58. A methodof detecting multiple polymorphisms in a target sequence comprising: a.adding a probe to a sample comprising the target, wherein said probecomprises: i. an oligonucleotide sequence comprising a 5′ end and a 3′end; ii. a Terminal Elongation Initiation (TEI) region comprising thelast 4 nucleotides at the 3′ end of the oligonucleotide sequence; andiii. a Duplex Anchoring (DA) region which forms an annealing complexwith a target sequence; wherein the oligonucleotide sequence comprisesat least two or more nucleotides corresponding to polymorphisms in thetarget sequence; b. incubating the probe and sample under conditions toallow hybridization of the probe to the target sequence; c. incubatingthe probe and sample under conditions to allow an elongation reaction tooccur; and d. detecting the elongation products from the reaction todetermine if the multiple polymorphisms are present in the sample. 59.The method of claim 58, wherein the TEI region comprises at least one ormore mismatches to the target sequence.